(Dilbilim) In drama, a protasis is the introductory part of a play, usually its first act. It was coined by the fourth-century Roman grammarian Aelius Donatus. He defined a play as being made up of three separate parts, the other two being epitasis and catastrophe
(Dilbilim) In linguistics, a protasis is the subordinate clause (the if-clause) in a conditional sentence. For example, in "if X, then Y", the protasis is "if X". The other clause ("then Y") is called the apodosis
The introductory or subordinate member of a sentence, generally of a conditional sentence; opposed to apodosis