tiercelet

CIDE DICTIONARY

tiercelet, 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.].

 The male of various falcons, esp. of the peregrine; also, the male of the goshawk.  Encyc. Brit.  [1913 Webster]