on the hour Definition

hour
noun

1. Sixty minutes, or the twenty-fourth part of a day.
2. The time indicated by a clock or watch.
3. An occasion or a point in time.

Example: an early hour
4. A special occasion or point in time.

Example: his finest hour
5. The time allowed or fixed for a specified activity.

Example: office hours
Form: hours
6. The distance travelled in an hour.

Example: two hours away from the airport
7. A time for action.

Example: The hour has come
8a. canonical hours;

Form: hours
8b. book of hours.

Form: hours

Idiom: after hours

After closing-time.

Idiom: at all hours

At irregular times, especially late at night.

Idiom: at the eleventh hour

At the last or latest moment.

Idiom: keep good hours

To lead a calm and regular life; to go to bed and rise early.

Idiom: on the hour

At exactly one, two, etc, o'clock.
Example: The train departs on the hour

Idiom: out of hours

Before or after usual working hours.

Etymology: 13c: from Greek hora.