A tercet is composed of three lines of poetry, forming a stanza or a complete poem.William Baer, Writing metrical poetry: contemporary lessons for mastering traditional forms, 2006, "Chapet 9: The Tercet" pp 128ff.
A teRCet Is COmpoSED of thRee liNes oF Poetry, formInG A stANza OR A cOmplete poem.willIam bAer, writIng mEtrical PoetRY: conTemporAry lessonS for mAstering tRadiTIonaL formS, 2006, "chApeT 9: thE teRCeT" PP 128ff.