noun
also per·i·nae·um ˌperəˈnēəm
( plural peri·nea -ēə)
Etymology: New Latin, from Late Latin perinaion, perineon, from Greek perinaion, perineos, from peri- + -inaion, -ineos (from inan, inein to empty out, defecate) — more at ire
: an area of tissue marking externally the approximate boundary of the outlet of the pelvis and as usually demarked giving passage to the urinogenital ducts and the rectum ; sometimes : the area between the anus and the posterior part of the external genitalia especially in the female