adjective

1. biting, cutting, caustic, or sarcastic, as speech, wit, etc.
2. causing corrosion
3. acting as a mordant

Etymology: ME mordent < OFr mordant, prp. of mordre, to bite < L mordere < IE *merd-, var. of base *mer-: see morbid

noun

1. a substance used in dyeing to fix the coloring matter, as a metallic compound that combines with the organic dye to form an insoluble colored compound, or lake, in the fiber of the fabric
2. an acid or other corrosive substance used in etching to bite lines, areas, etc. into the surface

transitive verb