Webster's 1828 Dictionary
TIERCEL, TIERCELET
n.In falconry, a name given to the male hawk, as being a third part less than the female.
Webster's 1913 Dictionary
TIERCEL; TIERCELET
Tier "cel, Tierce "let, n. Etym: [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 )
Defn: The male of various falcons, esp. of the peregrine; also, the male of the goshawk. Encyc. Brit.
New American Oxford Dictionary
tiercel
tier cel |ˈti (ə )rsəl ˈtɪərsəl |(also tercel ) ▶noun Falconry the male of a hawk, esp. a peregrine or a goshawk. Compare with falcon.
Oxford Dictionary
tiercel
tiercel |ˈtɪəs (ə )l | ▶noun variant spelling of tercel.
The Wordsmith Dictionary