horsepower

horse +‎ power: the unit was originally defined as the amount of power that a horse could provide.

• (General American) enPR: hôrsʹpou'ər, IPA^(key): /ˈhɔɹsˌpaʊɚ/
• (Received Pronunciation) enPR: hôsʹpou'ə, IPA^(key): /ˈhɔːsˌpaʊə/

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horsepower (countable and uncountable, plural horsepowers or horsepower)

1. A non-metric unit of power (symbol hp) with various definitions, for different applications. The most common of them is probably the mechanical horsepower, approximately equal to 745.7 watts.
   • 2012 March 22nd, David Blockley, Engineering: A Very Short Introduction (309), Oxford University Press, →ISBN, chapter 2: “The age of gravity – time for work”, page 20:

     In the past, before the widespread adoption of SI units, the work that engines were capable of doing was compared with the work that horses could do – hence the term ‘horsepower’. Various people came up with various equivalencies, but the modern agreed definition is that 1 horsepower is 746 joules per second or 746 watts.

2. A metric horsepower (symbol often PS from the German abbreviation), approximately equal to 735.5 watts.
3. Strength

   political horsepower

• hp

• shorepower