infix Get Printable Handwriting (in-fix) 2 syllables Rhymes Learn It! Spelling Test Definition noun. a word element that is inserted within the root or stem of a word Example Sentence She used the infix 'un' to make the word 'happy' into 'unhappy'. Synonyms insert; embed; interpose Antonyms prefix; suffix Rhymes Two Syllable Rhymes (1) infix Share with your friends: