1. chemistry destruction by chemical action: a process by which something, especially a metal, is destroyed progressively by chemical action, as iron is when it rusts
2. corroded material: material produced by corrosion, e.g. rust
3. gradual destruction: the gradual destruction or undermining of something a steady corrosion of the public trust
4. result of corrosion: the condition produced by corrosion
[14th century. < late Latin corrosion-< Latin corros-, past participle of corrodere (see corrode)]