<p><strong>Noun</strong></p><ul><li>Also called iron rust.</li><li>the red or orange coating that forms on the surface of iron when exposed to air and moisture, consisting chiefly of ferric hydroxide and ferric oxide formed by oxidation.</li><li>any film or coating on metal caused by oxidation.</li><li>a stain resembling this coating.</li><li>any growth, habit, influence, or agency tending to injure, deteriorate, or impair the mind, character, abilities, usefulness, etc.</li><li>Plant Pathology. any of several diseases of plants, characterized by reddish, brownish, or black pustules on the leaves, stems, etc., caused by fungi of the order Uredinales.</li><li>a fungus causing this disease.</li><li>any of several other diseases of unknown cause, characterized by reddish-brown spots or discolorations on the affected parts.</li><li>reddish yellow, reddish brown, or yellowish red.</li></ul><p><strong>Verb</strong></p><ul><li>(used without object) to become or grow rusty, as iron.</li><li>to contract rust.</li><li>to deteriorate or become impaired, as through inaction or disuse.</li><li>to become rust-colored.</li></ul><p><strong>Verb (used with object)</strong></p><ul><li>to affect with rust.</li><li>to impair as if with rust.</li><li>to make rust-colored.</li></ul><p><strong>Adjective</strong></p><ul><li>having the color rust.</li></ul><p><strong>Verb phrase</strong></p><ul><li>(of metal pipes, machinery, etc.) to decay and become unusable through the action of rust.</li><li>to join two metal pieces, as iron pipes, by causing the joint to rust.</li><li>to develop holes, breaks, or the like, because of rust.</li></ul>