Definition of ahorseback in English:

ahorseback

(also a horseback, a-horseback)

adverb

US
informal, archaic
  • On horseback.

Origin

Late 15th century; earliest use found in William Caxton (1415x24–1492), printer, merchant, and diplomat. Apparently from on horseback, with reduction of the first element.

Pronunciation

ahorseback

/əˈhɔːsbak/