fissures Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition plural noun. narrow openings or cracks in a surface. Example Sentence The fissures in the sidewalk were getting bigger. More Example Sentences Fissures can form during earthquakes. Synonyms cracks; splits; openings Antonyms closure; bond Hear It! Say It! Write It! fissures Switch to cursive Start Share with your friends: