periods Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition plural noun. units of time marked by specific events or activities. Example Sentence Pangaea broke apart during the Triassic and Jurassic Periods... More Example Sentences Each class lasts for four periods. Synonyms intervals; durations; spans Antonyms comma Hear It! Say It! Write It! periods Switch to cursive Start Share with your friends: