Why are dictionaries called dictionaries?
One could argue that dictionaries are called as such because they tell the user how to say things. Or you could say that the Latin word dictio means ‘a word’, and so a dictionary might be seen as a compendium of words.
In fact, the word ‘dictionary’ (in its Latin form dictionarius) appears to have been coined by the Englishman John of Garland in the early 13th century as the title of a children’s textbook written as a guide to Latin composition, and Garland makes clear in his introduction that he is thinking of dictio not so much in its sense ‘word’ but in its sense ‘connected speech’, because by using his guide the learner will be able to put words together to form connected speech.
See other FAQs about dictionaries.