from
The Collaborative International Dictionary of English v.0.48
Protasis \Prot"a*sis\ (pr[o^]t"[.a]*s[i^]s), n. [L., fr. Gr.
pro`tasis, fr. protei`nein to stretch before, forward; pro`
before + tei`nein to stretch.]
1. A proposition; a maxim. --Johnson.
[1913 Webster]
2. (Gram.) The introductory or subordinate member of a
sentence, generally of a conditional sentence; -- opposed
to {apodosis}. See {Apodosis}.
[1913 Webster]
3. The first part of a drama, of a poem, or the like; the
introduction; opposed to {epitasis}. --B. Jonson.
[1913 Webster]