rust

Definition

The deteriorated state of iron or steel as a result of moisture and oxidation; it consists mostly of iron(III) oxide (ferric oxide) and iron(II) oxide (ferrous oxide).

Etymology

From Middle English rust, rost, roust, from Old English rust, rūst (“rust”), from Proto-West Germanic *rust, from Proto-Germanic *rustaz (“rust”), from Proto-Indo-European *rudʰso- (“red”), from Proto-Indo-European *h₁rewdʰ- (“red”). Cognate with Scots roust (“rust”), Saterland Frisian rust (“rust”), West Frisian roast (“rust”), Dutch roest (“rust”), German Rost (“rust”), Danish rust (“rust”), Swedish rost (“rust”), Norwegian rust, ryst (“rust”), Finnish ruoste, Estonian rooste. Related to red.

Example Sentences

• "The rust on my bicycle chain made cycling to work very dangerous."
• "copper rust"