English
horsebreaker
From horse + breaker.
Proto-Germanic *hrussą ‘horse’
Proto-West Germanic *hross ‘horse’
Old English hors ‘horse’
Middle English hors ‘a horse’
English horse
Proto-Indo-European *bʰreg- ‘to break’
…
Proto-West Germanic *brekan ‘to break’
Old English brecan ‘to break’
Middle English breken ‘to break’
Middle English brekere ‘a transgressor or violator’
English breaker
Today it means
noun One who trains, or breaks in, horses.
Language periods are conventional ranges, not dates for this word.
Etymograph / horsebreaker