ottava rima

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A stanza of verse consisting of eight lines in iambic pentameter rhyming abababcc.

Century Dictionary and Cyclopedia

1. n. An Italian form of versification consisting of eight lines, of which the first six rime alternately and the last two form a couplet, the lines being in the proper Italian meter, the heroic of eleven syllables. Byron employed it in his “Beppo” and “Don Juan,” using lines of eleven or often of ten syllables.

GNU Webster's 1913

1. (Pros.) A stanza of eight lines of heroic verse, with three rhymes, the first six lines rhyming alternately and the last two forming a couplet. It was used by Byron in “Don Juan,” by Keats in “Isabella,” by Shelley in “The Witch of Atlas,” etc.

WordNet 3.0

1. n. a stanza of eight lines of heroic verse with the rhyme scheme abababcc