The Collaborative International Dictionary of English v.0.48:

Epiphonema \Ep`i*pho*ne"ma\, n. [L., fr. Gr. 'epifw`nhma, fr.
   'epifwnei^n to mention; 'epi` + fwnei^n to speak.] (Rhet.)
   An exclamatory sentence, or striking reflection, which sums
   up or concludes a discourse.
   [1913 Webster]