Hour
The hour (common symbol: h or hr, h being the international form of the symbol) is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds. It is approximately 1⁄24 of a mean solar day.
An hour in the Universal Coordinated Time (UTC) time standard can include a negative or positive leap second, and may therefore have a duration of 3,599 or 3,601 seconds for adjustment purposes.
Although it is not a standard defined by the International System of Units (SI), the hour is a unit accepted for use with SI, represented by the symbol h.
The Middle English word ure first appears in the 13th century, as a loanword from Old French ure, ore, from Latin hōra.Hora, in turn, derives from Greek ὥρα ("season, time of day, hour"). In terms of the Proto-Indo-European language, ὥρα is a cognate of English year and is derived from the Proto-Indo-European word *i̯ēro- ("year, summer").
The ure of Middle English and the Anglo-French houre gradually supplanted the Old English nouns tīd (which survives in Modern English as tide) and stund. Stund is the progenitor of , which remains an archaic synonym for hour. Stund is related to the Old High German stunta (whence German Stunde, "hour, lesson"), from Germanic *stundō ("time, interval, while").
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