crystals Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition plural noun. solid substances with a regular shape and structure. they form when liquids cool and harden. Example Sentence We made crystals in science class. More Example Sentences Some crystals are used in jewelry making. Synonyms gems; minerals; stones Antonyms black rock Hear It! Say It! Write It! crystals Switch to cursive Start Share with your friends: