tenderloin (n.)youdaoicibaDictYouDict[tenderloin 词源字典]
1828, "tender part of a loin of pork or beef," from tender (adj.) + loin. The slang meaning "police district noted for vice" appeared first 1887 in New York, on the notion of the neighborhood of the chief theaters, restaurants, etc., being the "juciest cut" for graft and blackmail.[tenderloin etymology, tenderloin origin, 英语词源]