adj. & n.
--adj.
1. (of sarcasm etc.) caustic, biting.
2 pungent, smarting.
3 corrosive or cleansing.
4 (of a substance) serving to fix colouring-matter or gold leaf on another substance.
--n. a mordant substance (in senses 3, 4 of adj.).
Derivatives:
mordancy n. mordantly adv.
Etymology: ME f. F, part. of mordre bite f. L mordere