a period of time equal to one twenty-fourth of a mean solar or civil day and equivalent to 60 minutes

He slept for an hour.

any specific one of these 24 periods, usually reckoned in two series of 12, one series from midnight to noon and the second from noon to midnight, but sometimes reckoned in one series of 24, from midnight to midnight

He slept for the hour between 2 and 3 a.m. The hour for the bombardment was between 1300 and 1400.

any specific time of day; the time indicated by a timepiece

What is the hour?

a short or limited period of time

He savored his hour of glory.

a particular or appointed time

What was the hour of death? At what hour do you open?

a customary or usual time

When is your dinner hour?

the present time

the man of the hour.

hours,

time spent in an office, factory, or the like, or for work, study, etc.

The doctor's hours were from 10 to 4. What an employee does after hours is his or her own business.

customary time of going to bed and getting up

to keep late hours.

(in the Christian church) the seven stated times of the day for prayer and devotion.

the offices or services prescribed for these times.

a book containing them.

distance normally covered in an hour's traveling

We live about an hour from the city.

Astronomy . a unit of measure of right ascension representing 15?, or the twenty-fourth part of a great circle.

a single period, as of class instruction or therapeutic consultation, usually lasting from 40 to 55 minutes. Compare clock-hour .

Education . Also called credit hour. one unit of academic credit, usually representing attendance at one scheduled period of instruction per week throughout a semester, quarter, or term.

the Hours, Classical Mythology . the Horae.

of, pertaining to, or noting an hour. ?

one's hour

Also, one's last hour. the instant of death

The sick man knew that his hour had come.

any crucial moment.