[mor.dant] adj [ME, fr. MF, prp. of mordre to bite, fr. L mordere; perh. akin to Skt mrdnati he presses, rubs] (15c) 1: biting and caustic in thought, manner, or style: incisive "a ~ wit"
2: acting as a mordant
3: burning, pungent syn see caustic -- mor.dant.ly adv
[2]mordant n (1791) 1: a chemical that fixes a dye in or on a substance by combining with the dye to form an insoluble compound
2: a corroding substance used in etching [3]mordant vt (1836): to treat with a mordant