rusty adj.

"red oxide of iron, red coating which forms on the surface of iron exposed to the air," Old English rust "rust," in late Old English also figurative, "anything tending to spiritual corrosion, a moral canker," related to rudu "redness," from Proto-Germanic *rusta- (source also of Frisian rust, Old High German and German rost, Middle Dutch ro(e)st), from PIE *reudh-s-to- (source also of Lithuanian rustas "brownish," rūdėti "to rust;" Latin robigo, Old Church Slavonic ruzda "rust"), from suffixed form of root *reudh- "red, ruddy."

As a morbid condition of plants caused by fungal growth, from mid-14c. U.S. colloquial rust-bucket for "old car or boat" is by 1945. Rust Belt "decayed urban industrial areas of mid-central U.S." (1984) was popularized in, if not coined by, Walter Mondale's presidential campaign.

adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.