Origin: [OF. plate a plate of metal, a cuirsas, F. plat a plate, a shallow vessel of silver, other metal, or earth, fr. plat flat, Gr. . See Place, n.] Wiktionary (0.00 / 0 votes) Rate this definition: plate (Noun) A dish from which food is served or eaten. I filled my plate from the bountiful table. plate (Noun) The contents of such a dish. I ate a plate of beans. plate (Noun) A course at a meal. The meat plate was particularly tasty. plate (Noun) A flat metallic object of uniform thickness.