“Ottava Rima: In prosody a stanza of eight lines rhyming a-b-a-b-a-b-c-c. The form, which arose in Italy in the 14th century, was used by Boccaccio, Tasso, Ariosto, and many other Italian poets. In English is is usually written in iambic pentameters. It was used, for example, by Keats in ‘Isabella‘ (1820); in ‘Don Juan,’ Byron strikes the mock-heroic, almost burlesque note that has come to be associated with the form.”
Excerpted from: Murphy, Bruce, ed. Benet’s Reader’s Encyclopedia, Fourth Edition. New York: Harper Collins, 1996.