planulae Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. the free-swimming, ciliated larva of certain coelenterates. Example Sentence The marine biologist studied the development of planulae in various species of coral. Synonyms larva; polyp; hydra Antonyms adult; mature organism Hear It! Say It! Write It! planulae Switch to cursive Start Share with your friends: