'Plate' shares its root with 'platypus' (flat-footed) and possibly Plato himself ('the broad one').
A flat dish from which food is eaten or served; also, a thin, flat sheet of metal, glass, or other material.
From Old French 'plate' (thin piece of metal) and Medieval Latin 'plata' (plate of metal, silver), from Vulgar Latin *plattus (flat, broad), from Greek 'platys' (broad, flat), from the PIE root *pleth₂- (to spread out, flat). The same Greek root gave English 'platitude,' 'platform,' 'plaza,' and 'platypus' (flat-footed). The shift from 'flat piece of metal' to 'dish for food' occurred because medieval diners ate off flat metal discs rather than bowls