tiercel noun. 
['tɪǝs(ǝ)l] Also tercel 
['tǝ:s(ǝ)l]. 
ME.[Old French 
tercel, 
terçuel (mod. 
tiercel) from Proto-Romance dim. of Latin 
tertius THIRD adjective etc.; perh. so named from the belief that the third egg of a clutch produced a male, or from the male being a third smaller than the female. Spelling and pronunc. infl. by mod. French or 
TIERCE noun1.]
Falconry. The male of any kind of falcon; 
esp. that of the peregrine falcon (in full 
tiercel-gentle) or of the goshawk.
Also 
 ■   tiercelet 
[-lɪt] noun LME.  [TahlilGaran] English Dictionary ▲