Tenderloin

n. 1. A strip of tender flesh on either side of the vertebral column under the short ribs, in the hind quarter of beef and pork. It consists of the psoas muscles. [ 1913 Webster ]

2. In New York City, the region which is the center of the night life of fashionable amusement, including the majority of the theaters, etc., centering on Broadway. The term orig. designates the old twenty-ninth police precinct, in this region, which afforded the police great opportunities for profit through conniving at vice and lawbreaking, one captain being reported to have said on being transferred there that whereas he had been eating chuck steak he would now eat tenderlion. Hence, in some other cities, a district largely devoted to night amusement, or, sometimes, to vice. [ Webster 1913 Suppl. ]