fastened Get Printable Handwriting Rhymes Hear It! Say It! Write It! Learn It! Spelling Test Definition verb. to attach or secure something firmly. Example Sentence He fastened his seatbelt when he got into the car. More Example Sentences He fastened his seatbelt before driving. Synonyms secured; attached; locked Antonyms loosened; released; unfastened Hear It! Say It! Write It! fastened Switch to cursive Start Rhymes Two Syllable Rhymes (1) fastened Share with your friends: