Database of Latvian Morphemes and Derivational Models: ideas and expected results (2025)

Abstract: In this paper, we describe “The Database of Latvian Morphemes and Derivational Models” – a large-scale corpus-based and manually validated database of Latvian derivational morphology currently in development at the University of Latvia. The database contains morpheme-level data – morphemes, incl. morpheme variants (allomorphs), morpheme types, morpheme homonymy/ homography resolu- tion, hierarchical relations between root morphemes, links to word families, and lemma-level data – incl. base form, morphemic segmentation, POS, grammatical features, derivational motivation (incl. compounding), word-family membership. The focus of the database is on providing linguistically accurate comprehensive data as a reliable basis for future work in different fields.

## introduction latvian (baltic group, indo-european language family) is a language with rich inflectional and derivational morphology. latvian inflectional morphology is extensively documented in linguistic literature, e.g., in academic grammars @xcite @xcite , and, by virtue of being paradigmatic (and, as far as nlp is concerned, also synchronic), relatively readily submits to formalization, at least at the conceptual, if not at the practical, level. over the last three decades, a number of approaches have been developed for latvian inflectional morphology processing, resulting in solutions for wordform analysis, generation, lemmatization, pos-tagging, etc., many of them using some version of a lexicon for greater precision; for a recent proposal and an overview of previous work, see @xcite . data on latvian inflection are also available in unimorph, which contains 136998 latvian inflected forms corresponding to 7548 paradigms foot_0 @xcite . the derivational structure of words is inherently less straightforward and involves several levels of complexity (see section 4), which need to be taken into account when developing derivational morphology processing technologies. early computational linguistic experiments on latvian derivational morphology have included attempts at describing possible approaches to automated morphemic segmentation of derived latvian words and morphemic and morphological analysis, e.g., @xcite , but, to the best of our knowledge, no comprehensive working computational linguistic models of latvian derivational morphology have been developed so far. it should be pointed out that up to now there has also been a lack of scientifically accurate large-scale resources (e.g., manually validated databases, lexicons) dedicated to latvian derivational morphology that could serve as a basis for developing and testing computational linguistic, e.g., rule-based, models. the most complete inventory of morphemically segmented latvian words (base forms) to date, organized into word families based on a common root or, in some cases, on a non-segmentable stem, is baiba metuzāle-kangere's "derivational dictionary of latvian" (a printed dictionary) @xcite . decisions about correct morphemic segmentation of complex words, derivational motivation or, e.g., allomorphism are not always straightforward for human linguists, and even less so for automated solutions unless the latter are trained or based on a large reliable body of data. in this paper, we describe a new digital resource (a database) dedicated to latvian derivational morphology, currently in development and to be made freely available to the public in 2026. the "database of latvian morphemes and derivational models" (dlmdm) is a corpus-based manually validated database in text format (.tsv files) with comprehensive data on the basic regularities of latvian derivational morphology. dlmdm is designed as a general reference resource, its focus is on producing a large structured manually validated set of data accurate and consistent from the point of view of linguistic theory for the general public for all kinds of future uses, incl. as a source for nlp research. ## related work printed dictionaries of morphemes and derivational dictionaries have been around for quite some time. particularly well represented are slavic languages, e.g. slovak @xcite , czech @xcite . there are also word-family dictionaries for other languages, e.g., german @xcite . two notable dictionaries reflecting different aspects of latvian morphemics and derivational morphology are "a derivational dictionary of latvian" @xcite and "latīn ¸u un griek ¸u cilmes vārddal ¸u vārdnīca" (a dictionary of latin and greek word parts) @xcite . metuzāle-kangere's dictionary is built around the concept of derivational families and is based on words extracted from two bilingual dictionaries. the last 20 years have seen an increase in digital resources containing some sort of morphemic and/or derivational information. such resources are often corpus-based in an effort to reflect actual contemporary language use, but differ by focus, scope and methodology (e.g. autoconstructed vs., less frequently, manually annotated). some of the recent examples include the database of lithuanian morphemics data @xcite , morpholex, a lexical database for english words with morphological variables @xcite , derinet @xcite , a lexical network of word-formation relations in czech, with autogenerated morphological segmentations of lemmas and identification of root morphs. universal derivations (uder) is a collection of harmonized lexical networks of various languages capturing word formation, especially derivation, in a cross-linguistically consistent annotation scheme based on a rooted tree data structure as used in the derinet 2.0 database. morphynet is a largescale, multilingual database that includes derivational and inflectional morphology data (over 13 million inflections and over 700 thousand derivations) for 15 languages extracted from wiktionary and 90 thousand derivations in 271 languages inferred automatically from the combination of mor-phynet and the universal knowledge core @xcite . unimorph 2.0 contains some data on latvian derivational morphology as supplementary structured data extracted from wiktionary -4235 complex words with a possible source word, a formally defined (pos:pos) wordformation model and means of derivation specified for each word foot_1 . the quality of these data depends on the accuracy of wiktionary and the level of detail is limited to what is available from that resource; e.g., derivation is not distinguished from compounding and formal means of derivation are not specified as morphemes of a certain type, but rather as word-initial or word-final strings of one or more morphemes merged together. morphemic, incl. derivational, information is also included in a number of broader scope lexical resources, e.g., the lexical database of english wordnet encodes some derivational relations, the celex lexical databases of english, dutch and german contain data on the derivational and compositional structure of words. several approaches for induction of derivational families from words extracted from large corpora have been developed, e.g. de-rivbase, derivcelex for german, derivbase.hr for croatian, etc. ## sources of complexity in data as a manually validated database, dlmdm's primary focus is on providing comprehensive linguistically accurate data. this means accounting for all kinds of phenomena in derivational morphology, not just productive regular derivation. in this section, we outline some of the major sources of difficulty in derivational morphological analysis of existing words. ## summary we hope that dlmdm will be useful as a reliable large-scale resource for further research on latvian derivational morphology from various perspectives, incl. computational linguistics, corpus linguistics and linguistics. future work might include a more in-depth analysis of the structure of borrowed words in latvian, esp. international words, words of classical (greek, latin) origin, incl. neoclassical compounds.