To Admit

1. (transitive) To allow to enter; to grant entrance (to), whether into a place, into the mind, or into consideration
2. (transitive) To allow (someone) to enter a profession or to enjoy a privilege; to recognize as qualified for a franchise.
3. (transitive) To concede as true; to acknowledge or assent to, as an allegation which it is impossible to deny

Synonyms: own up, confess

4. (transitive) To be capable of; to permit. In this sense, "of" may be used after the verb, or may be omitted.
5. (intransitive) To give warrant or allowance, to grant opportunity or permission (+ of).
6. (transitive) To allow to enter a hospital or similar facility for treatment.

In the sense "concede to be true", this is a catenative verb that takes the gerund (-ing). See Appendix:English catenative verbs

(to allow entry to): inlet, let in

(to recognise as true): acknowledge, own