Noun
(poetry) A highly structured poem consisting of six six-line stanzas followed by a tercet or envoy, for a total of thirty-nine lines.
Coordinate terms: pentina, triolet
(music) A chord comprising the first six members of the harmonic series.
Source: en.wiktionary.orgA "double sestina" is the name given to either: two sets of six six-line stanzas, with a three-line envoy (for a total of 75 lines), or twelve twelve-line stanzas, with a six-line envoy (for a total of 150 lines). Source: Internet
A "tritina" is a contraction of the sestina to three stanzas of three lines (tercets), with a one-line envoy. Source: Internet
Elizabeth Bishop (1965) Ferguson 1996 p. 1413–13 The sestina has been subject to some variations, with changes being made to both the size and number of stanzas, and also to individual line length. Source: Internet
“ ” First two stanzas of the sestina "Sestina" Edmund Gosse (1879) Effect The structure of the sestina, which demands adherence to a strict and arbitrary order, produces several effects within a poem. Source: Internet
As one commenter noted, the issue is like a sestina, with certain details—ropes, codes, last days—popping up rhythmically. Source: Internet
Don't fret, this isn't a sestina! Source: Internet