Urban Dictionary is a slang dictionary with your definitions. Define your world.
I heard someone use the word “kife” the other day, and I didn’t know what it was. My sister pulled up Urban Dictionary, and told me what the definition was.
It appears to be a wiki-type dictionary. You can add a word, and define existing ones. The definitions can be ranked, with the definitions with the highest ranking at the top.
Be careful, since anyone can post a definition, or define a new word/phrase, some are profane and vulgar.
In case your wondering, you can see the definition of “kife” here.