= repellent, n. 3b.

= water-repellent, n.

An agent or coating used to make something resistant to the absorption or passage of water.

Chiefly with modifying word. A substance applied to a fabric or surface in order to make it resistant to moisture, dirt, oil, etc. Cf. sense A. 2b.

(a) adj. impervious to water, as the plumage of ducks, the pubescence of many insects, etc.; (b) n. a substance which is impervious to or resists…

A hydrophobic substance.