Found this on the web:
Sometimes I have a concept stuck in my brain but the word is missing. I usually search for synonyms to a somewhat related word - but I figure this site is better than just googling a related word.
From their website: "This tool lets you describe a concept and get back a list of words and phrases related to that concept. Your description can be anything at all: a single word, a few words, or even a whole sentence. Type in your description and hit Enter to see the related words."