rectum: [16] Rectum is one of a range of words bequeathed to English by Latin rēctus ‘straight, correct’ (a distant relative of English right). Others include rectangle [16], rectify [14], and rectitude [15]. Rectum itself is short for rēctum intestīnum ‘straight intestine’ – a term contrasting the rectum with the convolutions of the remainder of the intestines. => direct, rectify, rectitude, right[rectum etymology, rectum origin, 英语词源]