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.

(Christianity) the hour of fasting and prayer before communion is to be taken. / (Ireland, informal) the hour between 2.30 pm and 3.30 pm that pubs formerly had to shut to comply with licencing laws.

(physics) a unit of electric charge, equal to the charge transferred by a current of one ampere in one hour through a specified point in a circuit, equal to 3600 coulombs.

The amount of work that can be done by one person in an hour.

(temporal location, idiomatic) Late into the night or early morning; when people ought to be sleeping.

The very early morning; the early morning hours; the nighttime hours following midnight, when most people are asleep.

(US) A period when traffic is light / time outside normal business hours

(idiomatic) The time at (or very close to) the start of the next hour of time.

Happening hourly, but at 30 minutes past each hour; ie, 08:30, 09:30 etc. / Happening on the hour and at 30 minutes after the hour. / (soccer) At thirty minutes into a half.