prevents Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition verb. keep from happening or arising; to hold or keep back Example Sentence Exposure to the hepatitis virus prevents a person from donating blood. Synonyms hinder; forbid; avert; frustrate; prohibit; stop Antonyms allow; permit; let Hear It! Say It! Write It! prevents Switch to cursive Start Share with your friends: