means A flat, usually round dish on which food is served, eaten from, or displayed.

from From Old French 'plate,' meaning a flat piece of metal or armor, drawn from Medieval Latin 'plata' (a thin sheet of metal), itself rooted in the idea of something flattened — a cousin of 'plat,' meaning flat. The sense of flatness came first; the dinner dish is simply a flat thing you put food on. The same flat-metal ancestry gives us 'plate armor' and 'silver plate,' so your supper sits on a word that once meant a knight's breastplate.