ribosomes Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. intercellular structure where protein synthesis occurs in the cell Example Sentence Bacterial ribosomes are complexes made of three RNA molecules and more than 50 proteins. Synonyms factory; output; machine Antonyms inactive Hear It! Say It! Write It! ribosomes Switch to cursive Start Share with your friends: