reentrant

[ree-en-truh nt] /riˈɛn trənt/
adjective
1.
reentering or pointing inward:
a reentrant angle.
noun
2.
a reentering angle or part.
3.
a person or thing that reenters or returns:
Reentrants to the engineering program must take the introductory course again.
4.
Physical Geography. a prominent indentation in a coastline.
Compare salient (def 6).
Also, re-entrant.
Origin
1775-85; re- + entrant