sestet

[se-stet, ses-tet] /sɛˈstɛt, ˈsɛs tɛt/
noun
1.
Prosody. the last six lines of a sonnet in the Italian form, considered as a unit.
Compare octave (def 4a).
2.
sextet (def 2).
Origin
1795-1805; < Italian sestetto sextet, equivalent to sest(o) (< Latin sextus sixth) + -etto -et
British Dictionary definitions for sestet

sestet

/sɛˈstɛt/
noun
1.
(prosody) the last six lines of a Petrarchan sonnet
2.
(prosody) any six-line stanza
3.
another word for sextet (sense 1)
Word Origin
C19: from Italian sestetto, from sesto sixth, from Latin sextus, from sex six
Word Origin and History for sestet
n.

1801, from Italian sestetto, diminutive of sesto "sixth," from Latin sextus (see Sextus).