noun

1. Any substance used to facilitate the fixing of a dye to a fibre; usually a metallic compound which reacts with the dye using chelation.

2. Any corrosive substance used in etching.

3. A glutinous size used as a ground for gilding, to make the gold leaf adhere.

Synonyms: etchant

verb

1. To subject to the action of, or imbue with, a mordant.

   “Mordant these goods for dyeing.”

adjective

1. Having or showing a sharp or critical quality

2. Serving to fix a dye to a fibre.

Synonyms: biting, caustic, keen, sarcastic, severe