reinforcements Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. 1 a device designed to provide additional strength; 2 a military operation often involving new supplies of men and materiel to strengthen a military force Example Sentence The general requested reinforcements from headquarters. Synonyms support; backup; help Antonyms hindrance Hear It! Say It! Write It! reinforcements Switch to cursive Start Share with your friends: