what does it mean if a substance is caustic
Princeton's WordNet(0.00 / 0 votes)Rate this definition: 1  caustic(adj) any chemical substance that burns or destroys living tissue. 2  acerb, acerbic, acid, acrid, bitter, blistering, caustic, sulfurous, sulphurous, virulent, vitriolic(adj) harsh or corrosive in tone.