mordant

a. [ F., p. pr. of mordere to bite; L. mordere. See Morsel. ] 1. Biting; caustic; sarcastic; keen; severe. [ 1913 Webster ]

2. (Dyeing & Calico Printing) Serving to fix colors. [ 1913 Webster ]

n. [ F., originally, biting. ] 1. Any corroding substance used in etching. [ 1913 Webster ]

2. (Dyeing & Calico Printing) Any substance, as alum or copperas, which, having a twofold attraction for organic fibers and coloring matter, serves as a bond of union, and thus gives fixity to, or bites in, the dyes. [ 1913 Webster ]

3. (Gilding) Any sticky matter by which the gold leaf is made to adhere. [ 1913 Webster ]

v. t. [ imp. & p. p. Mordanted; p. pr. & vb. n. Mordanting. ] To subject to the action of, or imbue with, a mordant; as, to mordant goods for dyeing. [ 1913 Webster ]