caus·tic/`kɔstɪk; ˈkɔːstɪk/ adj 1 a caustic remark/comment etc something you say that is extremely unkind or criticizes someone very severely 刻薄的话语/评论等 2 a caustic substance contains chemicals that can burn through things 〔物质〕腐蚀性的; 苛性的: caustic soda 苛性钠