English
kilowatt-hour
By surface analysis, kilowatt + hour, or, by surface analysis, kilo- + watt-hour.
Proto-Indo-European *yóh₁r̥ ‘year’
Ancient Greek ὥρᾱ ‘any defined period of time’
Latin hōra
Old French houre
Middle English houre
English hour
Today it means
noun A unit of energy equal to that provided by one kilowatt acting for one hour (3·6 × 10⁶ joules).
Language periods are conventional ranges, not dates for this word.
Etymograph / kilowatt-hour