Definition of mordant

• a. - Biting; caustic; sarcastic; keen; severe.
• a. - Serving to fix colors.
• n. - Any corroding substance used in etching.
• n. - 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.
• n. - Any sticky matter by which the gold leaf is made to adhere.
• v. t. - To subject to the action of, or imbue with, a mordant; as, to mordant goods for dyeing.