To spring with quick plunging leaps, descending with the fore legs rigid and the head held as low down as possible; -- said of a vicious horse or mule.

when the horse throws its hind legs/quarters in the air

A leap in the air with the head lowered and the back arched.

jump vertically, with legs stiff and back arched; "the yung filly bucked"

a young, unbroken horse that cowboys try to master at a rodeo

When a horse kicks out

Leaping into the air, back arched and landing on stiff forelegs

When a horse jumps upward and arches his back.

When a horse leaps in the air, keeping his forelegs stiff and his back arched, while lowering his head, sometimes kicking back in an effort to unseat a rider.

A short gymnastic horse without pommels and with one end elongated. It used to be used lengthwise for vaulting and sideways for learning pommel horse skills. It is not commonly used for vaulting any longer, but still is sometimes used as a training tool for pommel horse. Also called a pommel buck.