bareback
adjective, adverb uk/ˈbeə.bæk/ us/ˈber.bæk/
(ON HORSE)
无马鞍的（地）
without a saddle on the back of a horse that is being ridden
a bareback rider 不用马鞍的骑手
Is it difficult riding bareback? 不用马鞍骑马很难吗？
(SEX)
slang不使用避孕套性交
(of sexual activity) performed without using a condom