look up any word, like cunt:
 
1.
Corrosive and burning, but also interchangable for the word awesome.
"Man, when that shopping cart hit that wino, that was caustic"

"I went to this caustic party downtown, but then someone got stabbed"

"Sally is pretty caustic, when she's not hanging out with that pilgrim Luke"
by CapriceFidelity August 02, 2004
 
2.
Burning, Corosive.
No one was safe when the satirist H.L. Mencken unleashed his caustic wit.
by LarstaiT November 10, 2003
 
3.
capable of eating tissue paper
Sally: I saw Johnny eating some tissue paper.
Sue: Wow! He must be caustic!
by Verna N. September 30, 2006