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The hour (common symbol: h or hr) is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds. It is approximately 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, the hour is a unit accepted for use with SI, represented by the symbol h.〔(【引用サイトリンク】title=Non-SI units accepted for use with the SI, and units based on fundamental constants )〕 ==Etymology== 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 ("season, time of day, hour").〔 In terms of the Proto-Indo-European language, is a cognate of English ''year'' and is derived from the Proto-Indo-European word ' ("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 ''stound'', 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"). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「hour」の詳細全文を読む スポンサード リンク
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