external sex organ
"He pulled up his pants to cover his crotch after sitting on a cold metal bench for too long."
The area where something forks or branches, a ramification takes place.
"The old oak tree's massive crotch provided perfect shelter for the family of squirrels nesting in its upper branches."
To provide with a crotch; to give the form of a crotch to.
"The tailor carefully cut and sewed the fabric to properly crotch the new trousers for a comfortable fit."