Sometimes when I read a word I don’t know, instead of looking it up in the dictionary I just search Google. If the first hit is a link to a Wikipedia article or to a definition in an online dictionary, I deem that word a Thesaurus Word. It’s almost as if the word exists just to be used by people with (a) large vocabularies, or (b) plenty of time to thesaurusize.
Cases in point: quotidian, hegemony, prevarication.