The Collaborative International Dictionary
Protactic
Protactic \Pro*tac"tic\ (pr[-o]*t[a^]k"t[i^]k), a. [Gr. protaktiko`s placing or placed before, fr. prota`ssein to place in front; pro` before + ta`ssein to arrange.] Giving a previous narrative or explanation, as of the plot or personages of a play; introductory.
Wiktionary
protactic
a. Giving a previous narrative or explanation, as of the plot or personages of a play; introductory.