Origin: 1375–1425; < Latin admittere, equivalent to ad-ad- + mittere to send, let go; replacing late Middle English amitte, with a-a-5 (instead of ad-) < Middle French amettre < Latin, as above
early 15c., "let in," from L. admittere "to allow to enter, let in," from ad- "to" + mittere "let go, send" (see mission). Sense of "to concede as valid or true" is first recorded 1530s. Related: Admittedly (1804).