The Collaborative International Dictionary
Epideictic \Ep`i*deic"tic\, a. [Gr. ?, fr. ? to show forth, display; 'epi` + ? to show. Cf. Epidictic.] Serving to show forth, explain, or exhibit; -- applied by the Greeks to a kind of oratory, which, by full amplification, seeks to persuade.
Wiktionary
a. Of or pertaining to rhetoric of ceremony, declamation, and demonstration, most often the rhetoric of funerals and other formal events. One of the three branches, or "species" (eidē), of rhetoric as outlined by Aristotle.
Wikipedia
The epideictic oratory, also called ceremonial oratory, or praise-and-blame rhetoric, is one of the three branches, or "species" (eidē), of rhetoric as outlined in Aristotle's Rhetoric, to be used to praise or blame during ceremonies.
Usage examples of "epideictic".
For Wynne-Edwards, epideictic behaviour is deliberate massing in crowds to facilitate population estimation.
There is no direct evidence that any aggregations are in fact epideictic, but just suppose some such evidence were found.
By definition, this would indicate that the calls of starlings constituted an epideictic display.