n. 1 a twenty-fourth part of a day and night, 60 minutes. 2 a time of day, a point in time (a late hour; what is the hour?). 3 (in pl. with preceding numerals in form 18.00, 20.30, etc.) this number of hours and minutes past midnight on the 24-hour clock (will assemble at 20.00 hours). 4 a a period set aside for some purpose (lunch hour; keep regular hours). b (in pl.) a fixed period of time for work, use of a building, etc. (office hours; opening hours). 5 a short indefinite period of time (an idle hour). 6 the present time (question of the hour). 7 a time for action etc. (the hour has come). 8 the distance traversed in one hour by a means of transport stated or implied (we are an hour from London). 9 RC Ch. a prayers to be said at one of seven fixed times of day (book of hours). b any of these times. 10 (prec. by the) each time o'clock of a whole number of hours (buses leave on the hour; on the half hour; at quarter past the hour). 11 Astron. 15ø of longitude or right ascension. after hours after closing-time. hour-hand the hand on a clock or watch which shows the hour. hour-long adj. lasting for one hour.
adv. for one hour. till all hours till very late.
[ ME ure etc. f. AF ure, OF ore, eure f. L hora f. Gk hora season, hour ]