horseback

adv. on the back of a horse

n. back of a horse

adj. pertaining to riding on the back of a horse

Equestrianism refers to the skill of riding or driving horses. This broad description includes both use of horses for practical, working purposes as well as recreational activities and competitive sports.
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Noun
1. the back of a horse
(hypernym) body part
(part-holonym) horse, Equus caballus
2. a narrow ridge of hills
(synonym) hogback
(hypernym) ridge
Adverb
1. on the back of a horse; "he rode horseback to town"; "managed to escape ahorse"; "policeman patrolled the streets ahorseback"
(synonym) ahorse, ahorseback

(n.)
The back of a horse.
  

(n.)
An extended ridge of sand, gravel, and bowlders, in a half-stratified condition.
  

Synonyms and related words:
across, astraddle, astride, by horse, chine, col, comb, esker, hogback, kame, mounted, on, on horseback, ridge, saddle, saddleback, spine, straddle, straddle-legged, straddleback