(uncountable) The act, process, or state of reinforcing or being reinforced.

(countable) A thing that reinforces.

(in the plural) Additional troops or materiel sent to support a military action.

(uncountable, behavioral psychology) The process whereby a behavior with desirable consequences comes to be repeated.

A small round white sticker placed around a punched hole in a piece of paper to prevent the binder's rings from tearing through the paper.