early 15c., "acceptance, reception, approval," from Latin admissionem (nominative admissio) "a letting in," noun of action from past-participle stem of admittere "admit, give entrance; grant an audience," of acts, "let be done, allow, permit," from ad "to" (see ad-) + mittere "let go, send" (see mission). Meaning "an acknowledging" is from 1530s. Literal sense of "act of allowing to enter, admittance," is from 1620s. As short for admission price, by 1792.
