infants Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. a very young child birth to 1 year who has not yet begun to walk or talk; Example Sentence There are two infants in the family. Synonyms baby; babe; small child Antonyms grown-up Hear It! Say It! Write It! infants Switch to cursive Start Share with your friends: