JMdict: a Japanese-Multilingual Dictionary
James BREEN
Monash University
Clayton 3800, Australia
jwb@csse.monash.edu.au

Abstract
The JMdict project has at its aim thecompilation of a multilingual lexical
database with Japanese as the pivot
language. Using an XML structure designed
to cater for a mix of languages and a rich setof lexicographic information, it has reacheda size of approximately 100,000 entries,
with most entries having translations inEnglish, French and German. The
compilation involves information re-use,with the French and German translations
being drawn from separately maintained
lexicons. Material from other languages isalso being included. The file is freely
available for research purposes and forincorporation in dictionary application
software, and is available in several WWW
server systems.

it is not surprising that there is considerable
interest in electronic lexical resources forJapanese in combination with otherlanguages.
2 Project Goals and Development
As mentioned above, the JMdict projectgrew out of the bilingual EDICT dictionary
project. The EDICT project began in theearly 1990s with a relatively simple goal of
producing a Japanese-English dictionary filethat could be used in basic software
packages to provide traditional dictionary
services, as well as facilities to assist reading
Japanese text. The format was (and is) quite
simple, comprising lines of text consistingof a Japanese word written using kanji
and/or kana, the reading (pronunciation) ofthat word in kana, and one or more English
translations.

1 Introduction
The JMdict project has as its primary goal
the compilation of a Japanese-multilingual
dictionary, i.e. a dictionary in which the
headwords are from the Japanese lexicon,
and the translations are in several otherlanguages. It may be viewed as a synthesisof a series of Japanese-Other Language
bilingual dictionaries, although, as discussed
below, there is merit in having thisinformation collocated.
The project grew out of, and has now
subsumed, an earlier Japanese-English
dictionary project (EDICT: Electronic
Dictionary) (Breen, 1995, 2004a). With
Japanese being an important language inworld trade, and with it being the second
most common language used on the WWW,

By the late 1990s, the file had outgrown its
humble origins, having reached over 50,000
entries, and having spun off a parallel
project for recording Japanese proper nouns(see below). The material has partly beendrawn from word lists, vocabulary lists, etc.
in the public domain, and supplemented bymaterial prepared by large numbers of users
and other volunteers wishing to contribute.
While it had been used in a variety ofsoftware systems, and as a source of lexicalmaterial in a number of projects, it was clearthat its structure was quite inadequate for thelexical demands being made by users. In
particular, it was not able to incorporate asuitable variety of information, nor represent
the orthographical complexities of thesource language. Accordingly, in 1999 it
was decided to launch a new dictionaryproject incorporating the information fromthe EDICT file, but expanded to include
translations from other languages with theJapanese entries remaining as the pivots.
The project goals were:a. a file format, preferably using arecognized standard, which would enable
ready access and parsing by a variety ofsoftware applications;b. the handling of orthographical andpronunciation variation within the single
entry. This addressed a major problem with
the EDICT format, as many Japanese words
can be written with alternative kanji andwith varying portions in kana (okurigana),
and may have alternative pronunciations.
The EDICT format required each variant tobe treated as a separate entry, which added
to the complexity of maintaining andextending the dictionary;c. additional and more appropriately
associated tagging of grammatical and otherinformation. Certain information such as thepart of speech or the source language of loan
words had been added to the EDICT file inparentheses within the translation fields, but
the scope was limited and the information
could not easily be parsed;
d. provisionfordifferentiation
between different senses in the translations.
While basic indication of polysemy had
been provided in the EDICT file byprepending (1), (2), etc. to groups oftranslations, the result was difficult to parse.
Also it did not support the case where asense or nuance was tied to a particularpronunciation, as occurs occasionally inJapanese;e. provision for the inclusion oftranslational equivalents from several
languages. The EDICT dictionary file wasbeing used in a number of countries, andseveral informal projects had begun todevelop equivalent files for Japanese andother target languages. A small JapaneseGerman file (JDDICT) had been released in
the EDICT format. There was considerable
interest expressed in having translations invarious languages collocated to enable suchthings as having a single reference file forseveral languages, cross-referencing of
entries, cross-language retrieval, etc. as wellas acting as a focus for the possible
development of translations for as yet
unrepresented languages;
f. provision for inclusion of examplesof the usage of words. As the file expanded,
many users of the file requested some formof usage examples to be associated with thewords in the file. The EDICT format was
not capable of supporting this;g. provision for cross-references torelated entries;
h. continued generation of EDICTformat files. As a large number of packages
and servers had been built around the
EDICT format, continued provision ofcontent in this format was considered
important, even if the information only
contained a sub-set of what was available.
An early decision was to use XML(Extensible Markup Language) as a format
for the JMdict file, as this was expected toprovide the appropriate flexibility in format,
and was also expected to be supported byapplications, parsing libraries, etc.
An examination was made of other available
dictionary formats to ascertain if a suitableformatting model was available. It was
known
that
commercial
dictionary
publishers has well-structured databases oflexical information, and some were moving
to XML, but none of the details wereavailable. A large number of bilingual
dictionary files and word lists were in the
public domain; however in general they onlyused very simple structures, and none could
be found which covered all the content
requirements of the project. The dictionary
section of the TEI (Text Encoding
Initiative), which at the time of writing has awell-developed document structure forbilingual dictionaries, was at that stage quite
limited (Sperberg-McQueen et al, 1999).
Accordingly, an XML DTD (Document
Type Definition) was developed which was
tailored to the requirements of the project.

The EDICT file was parsed and reformatted
into the JMdict structure, and at the sametime, many of the orthographical variants
were identified and merged. The initial
release of the DTD and XML-format file
took place in May 1999. At that stage, it
contained the English translations from the
EDICT file and the German translations
from the JDDICT file. As described below,
it has been expanded considerably sincethen, both in terms of number of entries andalso in multi-lingual coverage.
3 Project Status
The JMdict file was first released in 1999,
and updated versions are released 3-4 times
each year along with versions of the EDICT
file, which is generated at the same timefrom the same data files. The file now hasover 99,300 entries, i.e. the size of a
medium-large printed dictionary, and thegrowth in numbers of entries is now
relatively slow, with most updates dealing
with corrections and expansion of existing
entries.
The file is available under a liberal licencethat allows its use for almost any purpose
without fee. The only requirement is that its
use be fully acknowledged and that any files
developed from it continue under the same
licence conditions.
4 Structure
The JMdict XML structure contains one
element type: <entry>, which in turn
contains sequence number, kanji word, kana
word, information and translation elements.
The sequence number is used formaintenance and identification.
The kanji word and kana word elements
contain the two forms of the Japanese
headwords; the former is used for
representations containing at least one kanji
character, while the latter is forrepresentations in kana alone. The kanaword is effectively the pronunciation, but isalso an important key for indexing thedictionary file, as Japanese dictionaries areusually ordered by kana words. The
minimum content of these fields is a single
word in the kana word element. In addition,
each entry may contain information about
the words (unusual orthographical variant,archaic kanji, etc.) and frequency of use
information. The latter needs to be
associated with the actual words rather thanthe entry as a whole because somecombinations of kanji and kana words areused more frequently than others. (Forexample, 合気道 and 合氣道 areorthographical variants of the one word
(aikidô), but the former is more common.)The kana used in the elements follows
modern Japanese orthography, i.e. hiragana
is used for native Japanese words, andkatakana for loan words, onomatopoeicwords, etc.
In most cases an entry has just one kanji andone kana word (approx. 75%), or one kanaword alone (15%). In about 10% of entries
there are multiple words in one of theelements. In some cases a kana reading canonly be associated with a subset of the kanji
words in the entry. For example, soyokaze(そよかぜ: breeze) can be written either
微風 or そよ風 (the latter is more common
as そよ is a non-standard reading of the 微
kanji). However 微風 can also be
pronounced bifuu (びふう) with the same
meaning, but clearly this pronunciation
cannot be associated with the そよ風 form,
as the kana portion is read "soyo". XML
does not provide an elegant method forindicating a restricted mapping between
portions of two elements, so when such a
restriction is required, additional tags areused with each kana word supplying the
kanji word with which it may be validly
associated.
The information element contains general
information about the Japanese word or theentry as a whole. The contents allow forISO-639 source language codes (for loan

words),dialect
codes,
etymology,
bibliographic information and update
details.
The translation area consists of one or more
sense elements that contain at a minimum asingle gloss. Associated with each sense is aset of elements containing part of speech,cross-reference, synonym/antonym, usage,etc. information. Also associated with thesense may be restriction codes tying thesense to a subset of the Japanese words. For
example, 水気 can be pronounced suiki(すいき) and mizuge (みずけ); bothmeaning "moisture", but the former alone
can also mean "dropsy".
The gloss element has an attribute stating
the target language of the translation. In its
absence it is assumed the gloss is in English.
There is also an attribute stating the gender,
if for example, the part-of-speech is a noun
and the gloss is in a language with gendered
nouns. Figure 1 shows a slightly simplified
example of an entry. The <ke_pri> and<re_pri> elements indicate the word is amember of a particular set of common
words.
<entry><ent_seq>1206730</ent_seq><k_ele><keb>学校</keb><ke_pri>ichi1</ke_pri></k_ele><r_ele><reb>がっこう</reb><re_pri>ichi1</re_pri></r_ele><sense><pos>&n;</pos><gloss>school</gloss><gloss g_lang="nl" g_gend="fg">school</gloss><gloss g_lang="fr" g_gend="fg">école</gloss><gloss g_lang="ru" g_gend="fg">школа</gloss><gloss g_lang="de" g_gend="fg">Schule</gloss><gloss g_lang="de"g_gend="fg">Lehranstalt</gloss></sense></entry>

Fig. 1: Example JMdict entry
The potential to have multiple kanji andkana words within an entry brings attention

to the issues of homonymy, homography
and polysemy, and the policies for handlingthese, in particular the criteria for combining
kanji and kana words into a single entry. As
Japanese has a comparatively limited set ofphonemes there are a large number ofhomophonous words. For example, overtwenty different words have the kanarepresentation こうじょう (kôjô). If weregard homography as only applying towords written wholly or partly with kanji,
there are relatively few cases of it, however
they do exist, e.g. 川柳 when read
せんりゅう (senryû) means a comic poem,
but when read かわやなぎ (kawayanagi)means a variety of willow tree.
The combining rule that has been applied in
the compilation of the JMdict file is asfollows:
a. treat each basic entry as a triplet
consisting of: kanji representation, matchingkana representation, senses;
b. if for any basic entries two or moremembers of the triplet are the same,combine them into the one entry;i.
if the entries differ in kanjior kana representation, include theseas alternative forms;
ii.
if the entries differ in sense,
treat as a case of polysemy;c. in other cases leave the entries
separate.
This rule has been applied successfully in a
majority of cases. The main problems arise
where the meanings are similar or related, as
in the case of the entries: (放す, はなす, toseparate; to set free; to turn loose) and(離す, はなす, to part; to divide; toseparate), where the kana words are thesame and the meanings overlap. Japanesedictionaries are divided on 放す and 離す;
some keeping them as separate entries, andothers having them as the one entry with twomain senses. (The two words derive from acommon source.)
5 Parts of Speech and Related Issues
As languages differ in their parts of speech(POS), the recording of those details inbilingual dictionaries can be a problem (AlKasimi, 1977). Traditionally bilingual
dictionaries involving Japanese avoid
recording any POS information, leaving it tothe user to deduce that information from thetranslation and examples (if any). In theearly stages of the EDICT project, POS
information was deliberately kept to aminimum, e.g. indicating where a verb wastransitive or intransitive when this was notapparent from the translation, mainly toconserve storage space. As there are anumber of advantages in having POS
information marked in an electronic
dictionary file, a POS element was includedin the JMdict structure, and publicly
available POS classifications were used topopulate much of the file. About 30% of
entries remain to be classified; mostly nouns
or short noun phrases.
In the interests of saving space an early
decision had been made to avoid listing
derived forms of words. For example, theJapanese adjective 高い (takai) meaning"high, tall, expensive" has derived forms of
高さ (takasa) "height" and 高く (takaku)"highly". As this process is very regular,
many Japanese dictionaries do not carry
entries for the derived forms, and somebilingual dictionaries follow suit. Anothersuch example is the common verb form,
sometimes called a "verbal noun", which iscreated by adding the verb する (suru) "to
do" to appropriate nouns. The verb "tostudy" is 勉強する (benkyôsuru) where
勉強 is a noun meaning "study" in thiscontext. Again, Japanese dictionaries often
do not include these forms as headwords,
preferring to indicate in the body of an entry
that the formation is possible.

The omission of such derived forms meansthat care needs to be taken whenconstructing the translations so that the user
is readily able to identify the appropriate
translation of one of the derived forms.
In a multilingual context, the omission ofderived forms can have other problems. The
recording of する verbs only in their nounbase form has been reported to lead to somediscomfort among German users, as German
languageorthographicalconvention
capitalizes the first letters of nouns but notverbs (the WaDokuJT file has する verbs as
separate entries for this reason).
6 Inclusion and Maintenance of Multiple
Languages
As mentioned above, part of the interest in
having entries with translations in a range oflanguages came from the compilation of anumber of dictionary files based on orsimilar to the EDICT file. There are anumber of issues associated with theinclusion of material from other dictionary
files, in particular those relating to thecompilation policies: coverage, handling of
inflected forms, etc. (Breen, 2002) There isalso the major issue of the editing andmaintenance of the material, which has thepotential to become more complex as eachlanguage is incorporated.
The approach taken with JMdict has been to:a. maintain a core Japanese-English
file with a well-documented structure andset of inclusion and editing policies;b. encourage the development andmaintenance of equivalent files in otherlanguages paired with Japanese, which candraw on the JMdict/EDICT material as
required;c. periodically build the complete
multi-lingual JMdict from the different
components.
This approach has proved successful in thatit has separated the compilation of the filefrom the ongoing editing of the components,and has left the latter in the hands of thosewith the skills and motivation to perform thetask.
At the time of writing, the JMdict file hasover 99,300 entries (Japanese and English),of which 83,500 have German translations,
58,000 have French translations, 4,800 have
Russian translations and 530 have Dutch
translations. A set of approximately 4,500
Spanish translations is being prepared, withthe prospects that some 20,000 will beavailable shortly.
The major sources of these additionaltranslations are:a. Frenchprojects:

translations

from

two

i.
approximately
17,500entries have come from theDictionnaire français-japonais Project(Desperrier, 2002), a project totranslate the most common Japanesewords from the EDICT File into
French;ii.
a further 40,500 entries
drawn from the 仏語補完計画(French-Japanese Complementation
Project)
at
http://francais.sourceforge.jp/ (Thisproject is also based on the EDICT
file.)
b. German translations from the
WaDokuJT Project (Apel, 2002). This is alarge file of over 300,000 entries; however,unlike JMdict it includes many phrases,
proper nouns and inflected forms of verbs,
etc. The overlap of coverage with JMdict isquite high, leading to the large number of
entries that have been included in the JMdict
file.
One of the issues that can lead to problems
when incorporating translations from otherproject files is that of aligning thetranslations when an entry has several

senses. In the case of the Frenchtranslations, the project coordinator has
marked the translations of polysemous
entries with a sense code, thus enabling thetranslations to be inserted correctly whencompiling the final file. For other languages,
the translations are being appended to the set
English translations. The appropriate
handling of multiple senses is an item of
future work.
7 Examples of Word Usage
When the project was begun and the DTD
designed, it was intended that sets ofbilingual examples of usage of the entry
words would be included. For this reason an<example> element was associated witheach sense to allow for such example
phrases, sentences, etc, to be included.
In practice, a quite different approach has
been taken. With the availability since 2001
of
a
large
corpusofparallel
Japanese/English sentences (Tanaka, 2001),
it was decided to keep the corpus intact, andinstead provide for the association of
selected sentences from the corpus withdictionary entries via dictionary application
software (Breen, 2003b). This strategy,
which required the corpus to be parsed to
extract a set of index words for eachsentence, has proved effective at theapplication level. It also has the advantage
of decoupling the maintenance of thedictionary file from that of the example
corpus.
8 Related Projects
Apart from a few small word lists involving
several European languages, the only othermajor current project attempting to compile
a comprehensive multilingual database is the
Papillon project (e.g. Boitet et al, 2002). See
http://www.papillon-dictionary.org/ for a
full list of publications. The Papillon design
involves linkages based on word-senses asproposed in (Sérasset, 1994) with the finer
lexical structure based on Meaning-Text

Theory (MTT) (Mel'cuk, 1984-1996). At thetime of writing the Papillon database is stillin the process of being populated with
lexical information.
Closely related to the JMdict project is theJapanese-Multilingual
Named
EntityDictionary (JMnedict) project. This is adatabase of some 400,000 Japanese place
and person names, and non-Japanese namesin their Japanese orthographical form, alongwith a romanized transcription of theJapanese(Breen,2004b).
Somegeographical
names
have
Englishdescriptions: cape, island, etc. which are in
the process of being extended to otherlanguages. The JMnedict file is in an XML
format with a similar structure to JMdict.
Another multilingual lexical database is
KANJIDIC2 (Breen, 2004c), which contains
a wide range of information about the
13,039 kanji in the JIS X 0208, JIS X 0212
and JIS X 0213 character standards. Amongthe information for each kanji are the set ofreadings in Japanese, Chinese and Korean,
and the broad meanings of each kanji in
English, German and Spanish. A set of
Portuguese meanings is being prepared. The
database is in an XML format.
9 Applications
While there are a number of experimental
systems using the JMdict file, the only
application system using the fullmultilingual file at present is the Papillon
project server. Figure 2 shows the display
from that server when looking up the word
川柳. The author's WWWJDIC server(Breen, 2003a) uses the Japanese-English
components of the file. Figure 3 is an extractfrom the WWWJDIC display for the word
小人, which is an example of an entry withmultiple kana words, and senses restrictedby reading. (The (P) markers indicate themore common readings.)

Fig. 2: Papillon example for 川柳

Fig. 3: WWWJDIC example for 小人
The EDICT Japanese-English dictionary
file, which is generated from the same
database as the JMdict file, continues to be amajor non-commercial Japanese-English
lexical resource, and is used in a large
number of applications and servers, as wellas in a number of research projects.
10 Conclusion
The JMdict project has successfully
developed a multilingual lexical databaseusing Japanese as the pivot language. In
doing so, it has reached a lexical coveragecomparable to medium-large printed
dictionaries, and its components are used ina wide range of applications and research
projects. It has also demonstrated thepotential for re-use of material from related
and cooperating lexicon projects. The filesof the JMdict project are readily available
for use by researchers and developers, andhave the potential to be a significant lexical
resource in a multilingual context.

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