A corrosive substance, like hydrochloric acid, will eat away most things on which it is spilled. Watch out in Chemistry lab: you wouldn't want to destroy your homework, desk, or worse, your own skin by spilling something corrosive on it.
The word corrosive comes from the Latin word, corrodere, meaning "to gnaw away." Rodere (to gnaw) is the same root word for rodent, so you can remember the word corrosive because something that is corrosive gnaws through things like a rodent. The adjective corrosive is also used to describe something that is bitingly or spitefully sarcastic. If you're known for your corrosive wit, you probably don't win any popularity contests.
