Reinforcement

подкрепа

podkrepa

(thing that reinforces)

подкрепление

podkreplenie

(in plural: additional troops or materiel sent to support a military action)

подсилване

podsilvane

(act or state of reinforcing or being reinforced)

укрепване

ukrepvane

(act or state of reinforcing or being reinforced)

утвърждение

utvǎrždenie

(behavioral psychology: process whereby a behavior with desirable consequences comes to be repeated)