The Collaborative International Dictionary of English v.0.48:
Crotch \Crotch\ (kr[o^]ch; 224), n.; pl. Crotches
(kr[o^]ch"[e^]z). [Cf. Crotchet, Crutch.]
1. The angle formed by the parting of two legs or branches; a
fork; the point where a trunk divides; as, the crotch of a
tree. more specifically, the space on the human torso
between the two legs; also, the corresponding part between
the legs of a pair of pants, which is in contact with the
crotch of the wearer; as, pants with a tight crotch have
become very popular.
[1913 Webster +PJC]
2. (Naut.) A stanchion or post of wood or iron, with two arms
for supporting a boom, spare yards, etc.; -- called also
crane and crutch. --Totten.
3. (Billiards) In the three-ball carom game, a small space at
each corner of the table. See Crotched, below.
[Webster 1913 Suppl.]