means a unit of time equal to 60 minutes, one twenty-fourth of a day.

from From Old French 'hore' (and Latin 'hora'), drawn ultimately from Greek 'hōra', which meant a season, a time, or a fixed period — not yet pinned to sixty minutes. The same Greek root gives us 'horoscope' (literally 'observer of the hour') and lurks behind 'year' through a distant Indo-European cousin meaning 'season' or 'period.' The silent 'h' is a later Latinizing flourish — the English mouth never really pronounced it.