An apparatus, usually fuel-burning, electric or solar-powered, in which water is heated to be used directly as domestic hot water or process hot water (but not for supplying space heating, calorifiers etc, for which a boiler or furnace is used).

(idiomatic, of a person) Angry, agitated. / (idiomatic, colloquial, slang, of a person) Sexually aroused.

Hot water for use in industrial processes.

Water used, in any type of building, for domestic purposes, principally drinking, food preparation, sanitation and personal hygiene (but not including space heating, swimming pool heating, or processes such as commercial food preparation or clothes washing).

(simile, colloquial) Quickly, especially by purchase or consumption.

(intransitive, idiomatic) To behave inconsistently; to vacillate or to waver, as between extremes of opinion or emotion.

a cry of delight or enthusiasm

hot off the press

freshly printed / (by extension, of news) so interesting or sensational that its publication cannot be delayed

a supposed test for witchcraft in which a hot iron was applied to the skin (or the tongue) - the skin of a witch would be unharmed