Reentrant

1. Reentering; pointing inward.
2. (programming, of a mutual exclusion mechanism) Such that the corresponding lock can be reacquired by the locking thread.
3. (programming) That may be executed more than once at a time either by different threads, or because of recursion.
4. (transport, of a part of a rocket) Designed to return to the Earth's atmosphere.
5. (physiology) Of or pertaining to reentry (in the heart)
6. (music, of a ukulele or similar instrument) Having the strings not ordered according to pitch (having a re-entry)