| Noun | 1. | hr - a period of time equal to 1/24th of a day; "the job will take more than an hour"time unit, unit of time - a unit for measuring time periods 24-hour interval, day, mean solar day, solar day, twenty-four hour period, twenty-four hours - time for Earth to make a complete rotation on its axis; "two days later they left"; "they put on two performances every day"; "there are 30,000 passengers per day" sidereal hour - 1/24 of a sidereal day 30 minutes, half-hour - a half of an hour 15 minutes, quarter-hour - a quarter of an hour man hour, person hour - a time unit used in industry for measuring work quarter - a unit of time equal to 15 minutes or a quarter of an hour; "it's a quarter til 4"; "a quarter after 4 o'clock" |