to strengthen with some added piece, support, or material

to reinforce a wall.

to strengthen (a military force) with additional personnel, ships, or aircraft

to reinforce a garrison.

to strengthen; make more forcible or effective

to reinforce efforts.

to augment; increase

to reinforce a supply.

Psychology . to strengthen the probability of (a response to a given stimulus) by giving or withholding a reward.

something that reinforces.

a metal band on the rear part of the bore of a gun, where the explosion occurs.