also horsewhip, 1690s, from horse (n.) + whip (n.). As a verb, "to flog with a horse-whip," from 1768. Related: Horse-whipped; horse-whipping.
horse-race
horseradish
horse-shit
horseshoe
horsetail
horse-whip
horsewoman
horst
Horst Wessel
horsy
hortative