"horseback" in the noun sense
1. horseback
the back of a horse
2. hogback, horseback
a narrow ridge of hills
"horseback" in the adverb sense
1. horseback, ahorse, ahorseback
on the back of a horse
"he rode horseback to town"
"managed to escape ahorse"
"policeman patrolled the streets ahorseback"
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License