tercet n the cardinal number that is the sum of one and one and one Usage(s) The poem opens with a noted tercet: Midway upon the journey of our life . The word means "time rhythm," and it describes a flexible tercet that has the form of a syllogism and the force of a heroic haiku. Synonym(s) three 3 III trio threesome tierce leash troika triad trine trinity ternary ternion triplet terzetto trey deuce-ace