Definition of ahorseback in English:

ahorseback

(also a-horseback, a horseback)

adverb

US
archaic, informal
  • 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/