- proficient (Merriam Webster)
- cumulus (Dictionary.com … maybe)
- insuavity (Worthless Word for the Day)
… on the Latin side:
https://twitter.com/#!/latinwordaday/status/204712887435014144
https://twitter.com/#!/LewisandShort/status/204589638118158336
… and the Greek:
https://twitter.com/#!/LiddellandScott/status/204588826314817536