n. (pl. -ies) 1 a book that lists (usu. in alphabetical order) and explains the words of a language or gives equivalent words in another language. 2 a reference book on any subject, the items of which are arranged in alphabetical order (dictionary of architecture).
[ med.L dictionarium (manuale manual) & dictionarius (liber book) f. L dictio (as DICTION) ]