English

ahorseback

From a- + horseback.

A compound of a- + horseback

Proto-Indo-European *uds- ‘up, out’

Proto-Germanic *uz- ‘out-’

Proto-West Germanic *uʀ- ‘up, out, over’

English a-

Middle English horsbak

Today it means

adv On the back of a horse; horseback.

Language periods are conventional ranges, not dates for this word.

Etymograph / ahorseback