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.
[1913 Webster]