Source : Webster's Revised Unabridged Dictionary (1913)

Terza rima \Ter"za ri"ma\ [It., a third or triple rhyme.]
   A peculiar and complicated system of versification, borrowed
   by the early Italian poets from the Troubadours.

Source : WordNet®

terza rima
     n : a verse form with a rhyme scheme: aba bcb cdc, etc.