AskHistorians

Lindsey Davis has written over 20 novels about 'public investigators' in old Roman times. One of the things she's mentioned in essays is that there's very little recorded slang from that era. She assumption is that if you're going to the trouble of writing a scroll by hand [or having an expensive scribe do it for you] you're going to try and look as educated as you can; kind of how you're probably not going to see bumper stickers on a Bentley.