This is a frivolous post.
Yesterday I was working with a colleague on a poster presentation and I used the word nascent. He didn't know it, but he does now.
Strangely, the wikipedia page contains the word nascent.
Which reminded me of the time I was working as a tech writer. I put the word extensible in my CV, but the agent I was working for said “that's not a proper word” and made me take it out. Subsequently I went on to make my fortune doing XML.