groin

(noun) the crease at the junction of the inner part of the thigh with the trunk together with the adjacent region and often including the external genitals. Synonyms: inguen.

(noun) a curved edge formed by two intersecting vaults.

(noun) a protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away. Synonyms: breakwater, groyne, mole, bulwark, seawall, jetty.

(verb) build with groins. Example: "The ceiling was groined."