metal (n.)

an undecomposable elementary substance having certain recognizable qualities (opacity, conductivity, plasticity, high specific gravity, etc.), mid-13c., from Old French metal "metal; material, substance, stuff" (12c.), from Latin metallum "metal, mineral; mine, quarry," from Greek metallon "metal, ore" (senses found only in post-classical texts, via the notion of "what is got by mining"); originally "mine, quarry-pit," probably a back-formation from metalleuein "to mine, to quarry," a word of unknown origin. Perhaps related somehow to metallan "to seek after," but Beekes finds this "hardly convincing."

The concept was based on the metals known from antiquity: gold, silver, copper, iron, lead, and tin. As an adjective, "of or covered with metal," from late 14c. As short for heavy metal (rock music) by 1980. Metal-work "work, especially artistic work, in metal" is by 1724.

Definitions of metal
metal (n.)
any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.;
Synonyms: metallic element
metal (n.)
a mixture containing two or more metallic elements or metallic and nonmetallic elements usually fused together or dissolving into each other when molten;
Synonyms: alloy
metal (v.)
cover with metal;
metal (adj.)
containing or made of or resembling or characteristic of a metal; "the strange metallic note of the meadow lark, suggesting the clash of vibrant blades"- Ambrose Bierce;
Synonyms: metallic