This is a dictionary that was crowdsourced before crowdsourcing was a common online behavior.
Search for any word in the dictionary and what is the first Google Image that comes up?
Digitization has also made updating the dictionary far easier.
1520s, from Medieval Latin dictionarium "collection of words and phrases," from Latin dictionarius "of words," from dictio "word" (see diction). Probably first English use in title of a book was in Sir Thomas Elyot's "Latin Dictionary" (1538) though Latin Dictionarius was so used from early 13c. Grose's 1788 "Dictionary of the Vulgar Tongue" has "RICHARD SNARY. A dictionary."