ˈtərsə̇t noun
or tier·cet ˈtirsə̇t
( -s )
Etymology: Italian terzetto tercet, terzetto, from diminutive of terzo third, from Latin tertius — more at third
: a unit or group of three lines of verse:
a. : one of the three-line stanzas linked by rhyme in terza rima
b. : one of the two groups of three lines forming the sestet in an Italian sonnet