BAREBACK
bareback, barebacked
(adjective) riding without a saddle; “a bareback rider”
bareback, barebacked
(adverb) without a saddle; “she prefers to ride her horse bareback”
Source: WordNet® 3.1
Etymology
Adverb
bareback (not comparable)
Without a saddle.
(slang) Without a condom.
Synonyms
• condomless
Coordinate terms
• saddleback
Verb
bareback (third-person singular simple present barebacks, present participle barebacking, simple past and past participle barebacked)
(intransitive, slang) To have sex without a condom.
(intransitive, slang) To have, usually male to male, anal sex without a condom.
Source: Wiktionary
Bare"back`, adv.
Definition: On the bare back of a horse, without using a saddle; as, to
ride bareback.
Source: Webster’s Unabridged Dictionary 1913 Edition