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
The crotch of something such as a pair of trousers is the part that covers the area between the tops of your legs. They were too long in the crotch. the part of your body between the tops of your legs, or the part of a piece of clothing that covers this groin (Probably from crutch)
A stanchion or post of wood or iron, with two arms for supporting a boom, spare yards, etc
{i} forking, branching; place where something forks (i.e. area between the legs, etc.)