metal

A metal is a chemical element that is a good conductor of both electricity and heat and forms cations and ionic bonds with non-metals.

In chemistry, a metal (from Greek "μέταλλον" – métallon, "mine") is an element,compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions (cations). Those ions are surrounded by delocalized electrons, which are responsible for the conductivity. The solid thus produced is held by electrostatic interactions between the ions and the electron cloud, which are called metallic bonds.

{more info at http://en.wikipedia.org/wiki/Metal}