copperplate (n.)

malleable metallic element, noted for its peculiar red color, tenacity, malleability, and electric conductivity, late Old English coper, from Proto-Germanic *kupar (source also of Middle Dutch koper, Old Norse koparr, Old High German kupfar), from Late Latin cuprum, contraction of Latin Cyprium (aes) "Cyprian (metal)," after Greek Kyprios "Cyprus" (see Cyprus).

Ancient Greek had khalkos "ore, copper, bronze;" an old IE word for "ore, copper, bronze" is retained in Sanskrit ayah, Latin aes. Latin aes originally was "copper," but this was extended to its alloy with tin (see bronze), and as this was far more extensively used than pure copper, the word's primary sense shifted to the alloy and a new word evolved for "copper," from the Latin form of the name of the island of Cyprus, where copper was mined (the alchemists associated copper with Venus).

Aes passed into Germanic (which originally did not distinguish copper from its alloys) and became English ore. In Latin, aes was the common word for "cash, coin, debt, wages" in many figurative expressions. Chemical symbol Cu is from cuprum.

As "a copper coin," from 1580s; as "a vessel made of copper," 1660s. The adjective, "of or resembling copper," is from 1570s; the verb, "to cover with copper" is from 1520s.

mid-13c., "flat sheet of gold or silver," also "flat, round coin," from Old French plate "thin piece of metal" (late 12c.), from Medieval Latin plata "plate, piece of metal," perhaps via Vulgar Latin *plattus, formed on model of Greek platys "flat, broad" (from PIE root *plat- "to spread"). The cognate in Spanish (plata) and Portuguese (prata) has become the usual word for "silver," superseding argento via a shortening of *plata d'argento "plate of silver, coin."

From 14c. as "armor made of sheets of metal." Meaning "table utensils" (originally of silver or gold only) is from Middle English. Meaning "shallow dish on which food is served at table," now usually of china or earthenware, originally of metal or wood, is from mid-15c. Meaning "articles which have been covered with a plating of precious metal" is from 1540s.

In photography, "common rectangular piece of glass used to receive the picture," by 1840. The baseball sense "home base" is from 1857. Geological sense "nearly rigid part of the earth's lithosphere" is attested from 1904; plate tectonics is attested from 1967. Plate-glass for a superior kind of thick glass used for mirrors, shop-windows, etc., is recorded from 1729.