What's the difference between (humanly anatomical) "groin" and "crotch". According to the unbelievably helpful definitions from the OALD 6:
I can't find a pictorial comparison so I'm still very confused.
Yes, they are labels for the same area of the body but have different connotations, collocations and separate other meanings.
Groin is a technical word meaning: The groin is actually a group of five muscles that attach the thigh to the pelvis, and everyone has these muscles. They are also called the "adductors." Thus, one has an injury to the groin.
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. By extension, the crotch of a tree. One can have what men call crotch itch.
The crotch includes the groin and genitals whereas the groin is a group of muscles, technically. Very simple.
The groin is where the elastic sits in traditional fitted underwear (panties for women, tighty whities or briefs for men), on the inside of the top of the thigh. If you look at a simple plastic doll that has legs that can turn and change their angle from the body, the groin is the place where the two parts come together (body and leg), near where the genitals would be if a doll had genitals.
To understand crotch, there are two things to think about. One is the crotch of a tree. That's a place where the trunk forks, and you end up with something Y-shaped. It's the part of the tree that's most vulnerable to damage from an ice storm, because the main trunk could split in two there.
The second thing to think about is rappers who grab their crotch on stage. I once heard a rapper explain in an interview with Terri Gross on Fresh Air that this gesture comes from fear. I'm sure there are other explanations related to bravado.
At any rate, groin is a precise location on the body, but crotch is more vague, it's that general area that would be covered up with a fig leaf in certain paintings.
When you go to the doctor and want to show him or her a questionable mole or bump or rash or whatever, you would not say that it is in your crotch area. Well, you could, but then the doctor would think you are a little crude. In this context, it would be much better to use a more precise word to describe exactly where the concern is located.
The etymology of groin derives from late Middle English grynde, perhaps from Old English grynde ‘depression, abyss’. Crotch derives from mid 16th century (denoting an agricultural or garden fork, also a crutch): perhaps related to Old French croche ‘crozier, shepherd's crook’, based on Old Norse krókr ‘hook’; partly also a variant of crutch. Groin and crotch can commonly be used to refer to the same thing, but crotch can also be used for clothing (i.e. The crotch of a pair of jeans). "Crotch" can also mean the "angle or region of the angle formed by the junction of two parts or members, such as two branches or legs". "Groin" is more of an anatomical term which specifically refers to "the crease or hollow at the junction of the inner part of each thigh with the trunk, together with the adjacent region and often including the external genitals." Hope this helps :)
Sources: Google search "define groin" and "define crotch" and https://www.usingenglish.com/forum/threads/69676-Crotch-vs-groin
The difference is that the former is far more polite than the latter. Doctors treat patients with groin injuries, never crotch injuries.
Equally you don't hear infantry squaddies say that the sergeant is a pain in the groin. More likely it would be for him to be a a pain in the crotch.
The best definition of groin is from Farlex Partner Medical Dictionary:
Topographic area of the inferior abdomen related to the inguinal canal, lateral to the pubic region.
Sometimes used to indicate only the crease in the junction of the thigh with the trunk.
So the groin is really to one side or the other of the genitals.
On the other hand, crotch is :
A fork or forking; the parting of two legs or branches; as the crotch of a tree.
Often the two are used interchangeably in casual speech. "Crotch" is the right word to use for clothing or measuring for clothing.
Inside/Outside, like the difference between belly (the protrusion and surface area around the stomach) and stomach (the interior area of the belly).