1. 1. The act or process of corroding.
   2. The condition produced by corroding.
2. A substance, such as rust, formed by corroding.

[Middle English corosioun, corrosion of tissue, from Old French corrosion, from Medieval Latin corrōsiō, corrōsiōn-, the act of gnawing, from Latin corrōsus, past participle of corrōdere, to gnaw away. See corrode.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.