It is the standard unit of power response slope over time. 1 horse of power equals 746 Watts, though.

Thank you for clarifying. I was using the standard unit, since that is how I've always used it in, for example, conversations about cycling.

I stand corrected...

But over 1 hour, no?

No. 1 horsepower, this instant, equals 746 watts, this instant. An average of 1 horsepower over an hour equals an average of 746 watts over the same hour.

Ah right. 746W over 1 hour would be 746Wh.

Yes.

And, a horsepower-hour is a thing. Railroad locomotives are often used by other railroads than the owner (in the US). Those "foreign" uses are often tracked in terms of horsepower-hours.