Definition:Protasis/Linguistic Note

Linguistic Note on Protasis
The word protasis is from the Ancient Greek πρότασις (prótasis), from προτείνω (proteínō), meaning put forward, tender or propose, from πρό (pró) $+$ τείνω (teínō), meaning stretch.

The word has been adopted by the theatre world as a word meaning the introductory part of a play, usually its first act.

Really would not expect this word to come up in a serious mathematical exposition, but, you know, some people may come across it at some point.