(chemistry) Water containing deuterium instead of normal hydrogen (protium) (symbol D₂O); used as a moderator in nuclear reactors.

Resistant to the effects of water. / Made of or covered with material that doesn't allow water in. / (figuratively) Incapable of failing; unassailable.

To make waterproof or water-resistant.

A substance or preparation for rendering cloth, leather, etc., impervious to water.

A spout connected to a socket to provide water from the main water supply.

A plant of the species Citrullus lanatus, bearing a melon-like fruit.

A flow of water over the edge of a cliff. / (figuratively) A waterfall-like outpouring of liquid, smoke, etc. / (technical, computing, slang) Waterfall model

(intransitive) To fall like a waterfall. / (transitive) To drink (something) from a container by pouring it from a height so as not to touch one's lips to the rim. / (roller derby) Synonym of recycle

A guard dog.

To perform a function analogous to that of a watchdog; to guard and warn. / (electronics) To be continuously reset by a watchdog timer.