A time of day, usually in the afternoon or early evening, when a bar or pub offers its drinks at a discounted price.

(figuratively) The hour at which any major event planned for the future is set to begin, as used in United States military.

(idiomatic) The times of the day when traffic jams are commonplace, due mainly to people commuting to or from work.

The hand of a clock or watch face that revolves twice each day and indicates the hours.

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

(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.

(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.

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