noun

1. 1. a division of time, one of the twenty-four parts of a day; sixty minutes
   2. one of the twelve points on a clock, watch, etc. marking the beginning or end of such a division the ninth hour
2. a point or period of time; specif.,
   1. a fixed point or period of time for a particular activity, occasion, etc. the dinner hour
   2. an indefinite period of time of a specified kind his finest hour
   3. a period fixed for work, receiving patients, etc. office hours from 2 to 5
   4. the usual times for getting up or going to bed to keep late hours
3. the time of day as indicated by a timepiece or as reckoned from midnight to midnight, expressed in hours and minutes arrival at 14:30 hours
4. a measure of the distance usually covered in an hour two hours from New York to Philadelphia by rail
5. Astron. a sidereal hour; angular unit equaling 15° measured along the celestial equator
6. Eccles. a canonical hour or the prayers then said
7. ☆ Educ. a class session of approximately one hour: each hour of a course per week is a unit of academic credit

Etymology: ME < OFr hore < L hora < Gr hōra, hour, time, period, season < IE base *yē-, year, summer (< *ei-, to go) > year