-
Hour
An hour (symbol: h; also abbreviated hr.) is a unit of time conventionally reckoned as 1⁄24 of a day and scientifically reckoned as 3,599–3,601 seconds, depending on conditions.
The hour was initially established in the ancient Near East as a variable measure of 1⁄12 of the night or daytime. Such seasonal, temporal, or unequal hours varied by season and latitude. The hour was subsequently divided into 60 minutes, each of 60 seconds. Equal or equinoctial hours were taken as 1⁄24 of the day as measured from noon to noon; the minor seasonal variations of this unit were eventually smoothed by making it 1⁄24 of the mean solar day. Since this unit was not constant due to long term variations in the Earth’s rotation, the hour was finally separated from the Earth’s rotation and defined in terms of the atomic or physical second.
In the modern metric system, hours are an accepted unit of time defined as 3,600 atomic seconds. However, on rare occasions an hour may incorporate a positive or negative leap second, making it last 3,599 or 3,601 seconds, in order to keep it within 0.9 seconds of UT1, which is based on measurements of the mean solar day.
-
Hour (noun)
A time period of sixty minutes; one twenty-fourth of a day.
“I spent an hour at lunch.”
-
Hour (noun)
A season, moment, time or stound.
-
Hour (noun)
The time.
“The hour grows late and I must go home.”
-
Hour (noun)
Used after a two-digit hour and a two-digit minute to indicate time.
-
Hour (noun)
A distance that can be traveled in one hour.
“This place is an hour away from where I live.”
-
Houre (noun)
obsolete spelling of hour
-
Hour (noun)
a period of time equal to a twenty-fourth part of a day and night and divided into 60 minutes
“rates of pay were low, starting at £3.20 an hour”
“an extra hour of daylight in the winter evenings”
“a two-hour operation”
-
Hour (noun)
a more indefinite period of time
“during the early hours of the morning”
-
Hour (noun)
the distance travelled in one hour
“Ocean City is less than an hour away”
-
Hour (noun)
a time of day specified as an exact number of hours from midnight or midday
“the clock in the sitting room struck the hour”
-
Hour (noun)
a time specified on the twenty-four-hour clock
“the first bomb fell at 0051 hours”
-
Hour (noun)
the time as formerly reckoned from sunrise
“it was about the ninth hour”
-
Hour (noun)
a fixed period of time for an activity, such as work, use of a building, etc.
“the dinner hour”
“opening hours”
“licensing hours”
-
Hour (noun)
a particular point in time
“I wondered if my last hour had come”
“you can’t turn him away at this hour”
-
Hour (noun)
(in the Western (Latin) Church) a short service of psalms and prayers to be said at a particular time of day, especially in religious communities
“an organized life of prayer including the canonical hours”
-
Hour (noun)
15° of longitude or right ascension (one twenty-fourth part of a circle).