a. Any of various powdery or scaly reddish-brown or reddish-yellow hydrated ferric oxides and hydroxides formed on iron and iron-containing materials by low-temperature oxidation in the presence of water.
b. Any of various metallic coatings, especially oxides, formed by corrosion.
c. A stain or coating resembling iron rust.
2. Deterioration, as of ability, resulting from inactivity or neglect.
a. Rust fungus.
b. A plant disease caused by a rust fungus, characterized by reddish or brownish spots on leaves, stems, and other parts.
4. A strong brown.
v. rust·ed, rust·ing, rusts
1. To become corroded.
2. To deteriorate or degenerate through inactivity or neglect: My golf game has rusted from all those years of not playing.
3. To become the color of rust.
4. Botany To develop a disease caused by a rust fungus.
1. To corrode or subject (a metal) to rust formation.
2. To impair or spoil, as by misuse or inactivity.
3. To color (something) a strong brown.
[Middle English, from Old English rūst; see reudh- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus