Time to confess: tell us about a time when you used a word whose meaning you didn’t actually know (or were very wrong about, in retrospect).
When I was in my college years, the word I didn’t know was penultimate. I thought it meant beyond ultimate, as if. I got called on it at dinner one night, and brashly asserted my position. I was disabused of my belief by, of all things, a physics major. The Lit people at the table ignored me because I was, at the time, a mathematician. They knew we were wayward in our use of words, and accepted it as part of the humor of college life. The physics major knew it because he had used it in a physics paper and was told to leave the Lit words out of science.
My current favorite words are evanescent and preternatural. They both state in one word things that the Thesauri do not get in their synonyms. And the dictionaries use many words to explain them. So people should look them up and use them. You will be doing a service for those who want to know big words but don’t know where to start!