Hello, I wrote Jack Lynch, Professor at Rutledge Univ. of 18th Century Literature. His talks includes works involving dictionaries. He responded (concerning definition of dictionary) with "dictionary" has had a wide range of applications over the centuries.  Since 1631, the word "dictionary" has been used with this meaning:

    By extension: A book of information or reference on any
    subject or branch of knowledge, the items of which are
    arranged in alphabetical order; an alphabetical encyclopædia as a Dictionary of Architecture, Biography, Geography, of the Bible, of Christian Antiquities, of Dates, etc.

There are all sorts of reference works we'd be likely to call
other things  encyclopedias, gazetteers, and so on  that have been called dictionaries by their makers.  In these cases,

    the essential sense ‘word-book’ is supplanted by the
    accidental one of ‘reference book in alphabetical order’
    arising out of the alphabetical arrangement used in modern
    word-books.. My reason for contacting Professor Lynch was the result of a curriculum director denying my published phonetic dictionary to her school relating that the reference book was not a 'real' dictionary. Now the dictionary is in public library collections in Canada, Mexico, The Netherlands and, of course, since it's an American English Phonetic Dictionary, is in over 400 U.S. public libraries. I am the lexicographer and would like to include "Gabby's Wordspeller & Phonetic Dictionary" into the dictionary collection. And, since it's the only known phonetic dictionary currently in existence in either book or digital form, it has no category to list itself. Does it belong in a sub-category or does it require it's own category? There may be others come along now that this one has made the light of day.