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 ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.