ˈtirsəl noun
or ter·cel ˈtərs- ; or tas·sel ˈtas-
( -s )
Etymology: Middle English tercel, tassel, from Middle French tercel, tiercel, from (assumed) Vulgar Latin tertiolus, from diminutive of Latin tertius third; perhaps from the belief that every third egg in the nest produced a male — more at third
: a male of various hawks (as the peregrine falcon and the goshawk)