plural of Student Hour

Man-hour.

A full sixty-minute period (as opposed to a scheduled length of time that is called an "hour" but not equivalent to sixty minutes, such as a student hour).

plural of clock hour

plural of lunch hour

plural of light hour

plural of horsepower-hour

(electricity) A unit of energy equal to the amount of work a horse is capable of delivering during an hour.

(education, academics, US) A course credit based on the number of contact hours per week in class, for one given term or semester.

plural of credit hour