1. Covered or affected with rust; as, a rusty knife or sword; rusty wheat.
2. Impaired by inaction, disuse, or neglect. [Hector] in this dull and long-continued truce, Is rusty grown. (Shak)
3. Discoloured and rancid; reasty; as, rusty bacon.
4. Surly; morose; crusty; sullen. Rusty words.
5. Rust-coloured; dark. Rusty blood.
6. Discoloured; stained; not cleanly kept; filthy. The rustly little schooners that bring fire wood from the Brititsh provinces. (Hawthorne)
7. (Science: botany) Resembling, or covered with a substance resembling, rust; affected with rust; rubiginous.
Origin: Rustier; Rustiest.