Most probably you haven’t. Atleast I hadn’t, till today. Not sure from when they have it, but the dictionary app from Google is crisp, fast and accurate.
Google Dictionary provides definitions and synonyms in almost thirty different languages, pulled from a scope of different sources and impressively fast.
In addition to Google’s own database of definitions, looking up a word on the Dictionary website provides a list of definitions pulled from a variety of academically authoritative sources. You can mark words with the star button and come back to them later, see a list of recent searches and switch to translator resources or dictionaries for other languages.
It also has “Related phrases” feature which is useful to know the related phrases of the word.
Check out Google Dictionary