Groin
In anatomy, the area where the upper thigh meets the trunk.
More precisely, the fold or depression marking the juncture of the lower abdomen and the inner part of the thigh.
In sports medicine, 'groin injuries' are well known in pages of the sports section of newspapers.
<U>Etymology:</U> The word 'groin' is thought to have come from the Old English 'grynde' meaning an abyss or trench.
The groin forms a sort of trench when the thigh is flexed.