My vocabulary is reasonably large, and I too own a dictionary that is very, very thick. But I don't look up words in it to find out what they mean, I look them up to make certain I spelled them correctly. (Never could spell, ) I have always learned new words from the way they are used. (Which is maybe why I blithely put in a dumpload of madeup vocabulary in my latest manuscript,only to have my test readers throw up their hands in dismay.)