(weightlifting, informal) The activity of weightlifting, especially for the purposes of bodybuilding.

(chemistry) The compound obtained by the reaction of oxygen on iron. Either iron(II) oxide (old term ferrous oxide, chemical formula FeO) or iron(III) oxide (old term ferric oxide, chemical formula Fe₂O₃). Generally known as rust when hydrated.

A branding iron which is not bent into the shape of the mark but rather requires the user to write the desired brand (and thus allows writing any brand).

Covered with iron, steel, or some metal, armor-plated. / (figuratively) Solid or certain; not able to be disputed or questioned; irrefutable. / (figuratively) Rigorous; severe; exacting.

A metal-plated ship, vessel, or vehicle. / (military) An armor-plated warship.

A particular allotrope of iron.

A mixture of fine iron particles, unreacted iron oxide (ore), slag and charcoal residue.

(manner) In an ironic manner; in a way displaying irony. / (evaluative) Used to draw attention to an ironic aspect of a situation being described.

(obsolete, chemistry) iron(II) sulfate

finely powdered iron, which ignites spontaneously in air