Metals that contain iron such as steel.
Ferrous, in chemical science, indicates a bivalent iron compound (+2 oxidation state), as opposed to ferric, which indicates a trivalent iron compound (+3 oxidation state).
Outside of chemical science, ferrous is an adjective used to indicate the presence of iron. The word is derived from the Latin word ferrum ("iron"). Ferrous metals include steel and pig iron (with a carbon content of a few percent) and alloys of iron with other metals (such as stainless steel).