Crotch

In humans, the crotch is the bottom of the pelvis, the region of the body where the legs join the torso, and is often considered to include the groin and genitals.
Etymology.
"Crotch" is derived from "crutch"; it "was first used in 1539 to refer to a forked stick used as a farm implement." This region of the body is also described with other terms such as "groin" or the lower ventral area.
Depictions in artwork.
The human crotch has been depicted in artwork. In Paleolithic art, forms called tectiforms or quadrilaterals have sometimes been interpreted to be "quick visual guides, reminders to the imagination" of the female crotch, and typically do not represent the crotch hairs.
Classical marble statues depict females without pubic hair; in contrast statues of males "show curly pubic hair".
For much of the history of European art - "until the late seventeenth century" - references to the female crotch were approached from above: "Art usually expressed the sense of the vulva as a point at the bottom of the belly rather than as the meeting place at the top of the thighs."
Art therapists have noted "a triangular or vaginal shaped area in drawings by rape/sexual abuse victims".
Scope.
The semantic field of the term "crotch" is sometimes expanded to include objects which have a similar shape to the anatomical human crotch. This may include botanical structures such as the area where tree branches are joined together or mechanical structures which fork or branch or where ramification takes place. The term had also been expanded to include the joining together of asymmetrical surfaces in cue sports equipment or the corners of flat surfaces usually made of quarried slate.
In clothing.
In clothing, the crotch is the area of trousers, shorts, leggings etc. where the legs join. The bottom of the crotch is an end of the inseam. The crotch-region on smaller garments such as underwear are sometimes referred to as the "pouch". Loosely-fitted or bagginess in the crotch-region is sometimes associated with a lax, casual and easy-going approach to attires or garbs. 
Clothing that is tight-fitting in the crotch is sometimes referred to by informal terms such as a "man-bulge" or "moose-knuckle" on men, and a "camel toe" on women, especially if the woman's labia majora is conspicuous. Prolonged constrictive pressure of the crotch on the male genitals may increase the likelihood of detumescing.