Sun. Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. the star at the center of our solar system that provides light and heat. Example Sentence The abbreviation for Sunday. Sun. More Example Sentences Children play outside when the sun is out. Synonyms star; daylight; sunshine Antonyms abbreviation for Saturday Hear It! Say It! Write It! Sun. Switch to cursive Start Share with your friends: