Tiercel \Tier"cel\, Tiercelet \Tierce"let\, n. [OE. tercel, tercelet, F. tiercelet, a dim. of (assumed) tiercel, or LL. tertiolus, dim. fr. L. tertius the third; -- so called, according to some, because every third bird in the nest is a male, or, according to others, because the male is the third part less than female. Cf. {Tercel}.] (Falconry) The male of various falcons, esp. of the peregrine; also, the male of the goshawk. --Encyc. Brit.