[no obj.](of a horse) jump vertically with its head lowered, back arched, and legs drawn together, typically in an attempt to unseat its rider (马)低头弓背跳跃
noun
[often as modifier]an act or display of buckjumping (马的)低头弓背跳跃 a buckjump rider. 让马做腾跃动作的骑马者。