1. The oxyd of a metal; a substance composed of oxygen combined with a metal, and forming a rough coat on its surface. All metals except gold are liable to rust.

2. Loss of power by inactivity, as metals lose their brightness and smoothness when not used.

3. Any foul matter contracted; as rust on corn or salted meat.

4. Foul extraneous matter; as sacred truths cleared from the rust of human mixtures.

5. A disease in grain, a kind of dust which gathers on the stalks and leaves.

, v.t.

1. To cause to contract rust.

Keep up your bright swords, for the dew will rust them.

2. To impair by time and inactivity.