A period of time equal to thirty minutes, half an hour. / The time of thirty minutes past any particular hour.

(aviation) The time from the moment the aircraft door closes at departure of a revenue flight until the moment the aircraft door opens at the arrival gate following its landing. Block hours are the industry-standard measure of aircraft utilization.

A unit of electrical energy equal to the power of one watt in use for one hour; often used as a unit of electricity consumption

(physics) A measure of energy, one hundred watt-hours, or one-tenth of a UK "unit" of electricity.

(chiefly US) An event, particularly on radio or television, showcasing the talents of amateur performers.

(units of measure) A unit of time reckoned as ¹⁄₁₂ of a day's daylight or nighttime, varying according to season, latitude, and local weather.

A unit of electrical energy equal to that done by one terawatt acting for one hour.

plural of man-hour

plural of H-hour

plural of happy hour