ˌɹiːɪnˈfɔː(ɹ)smənt a military operation (often involving new supplies of men and materiel) to strengthen a military force or aid in the performance of its mission they called for artillery support an act performed to strengthen approved behavior a device designed to provide additional strength the cardboard backing was just a strengthener he used gummed reinforcements to hold the page in his notebook (psychology) a stimulus that strengthens or weakens the behavior that produced it information that makes more forcible or convincing his gestures provided eloquent reinforcement for his complaints