Achilles' heel Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. a portion or spot or area or the like that is especially or solely vulnerable; a small but fatal weakness Example Sentence His Achilles' heel is his quick temper. Synonyms vulnerable point; weakness; weak spot Antonyms strength Hear It! Say It! Write It! Achilles' heel Switch to cursive Start Share with your friends: