Variant form of epideictic; relating to rhetoric meant for display and impression rather than argument.
From Greek 'epideiknynai' with the English adjectival suffix '-ical' instead of '-ic', following the pattern of alternative adjective forms.
This is just the longer, more formal way of saying 'epideictic'—both refer to speech meant to dazzle and impress rather than convince, like a lawyer's dramatic closing argument!
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