UNHORSE
unhorse, dismount, light, get off, get down
(verb) alight from (a horse)
Source: WordNet® 3.1
Etymology
Verb
unhorse (third-person singular simple present unhorses, present participle unhorsing, simple past and past participle unhorsed)
To forcibly remove from a horse.
(by extension) To disrupt or unseat; to remove from a position.
Source: Wiktionary
Un*horse", v. t. Etym: [1 st pref. un- + horse.]
Definition: To throw from a horse; to cause to dismount; also, to take a
horse or horses from; as, to unhorse a rider; to unhorse a carriage.
Cowper.
Source: Webster’s Unabridged Dictionary 1913 Edition