The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Sestet (sextet)
Sestet (sextet): (1) Generally speaking, any six-line poem or stanza. (2) More specifically, the second part (the last six lines) of an Italian sonnet. The sestet succeeds the octave, which may pose a question or dilemma that the sestet answers or resolves, and usually follows the rhyme scheme cdecde, although variations occur.