(1):

(superl.) Resembling, or covered with a substance resembling, rust; affected with rust; rubiginous.

(2):

(superl.) Covered or affected with rust; as, a rusty knife or sword; rusty wheat.

(3):

(superl.) Impaired by inaction, disuse, or neglect.

(4):

(superl.) Discolored and rancid; reasty; as, rusty bacon.

(5):

(superl.) Surly; morose; crusty; sullen.

(6):

(superl.) Rust-colored; dark.

(7):

(superl.) Discolored; stained; not cleanly kept; filthy.