horse's legs
Literal meaning, rarely used outside the idiom 馬脚を現す.
stagehand playing a horse's hind legs
Refers to a performer who operates the back legs of a horse costume in traditional theater. This sense is historical and rarely used in modern conversation.
See also: 馬脚を現す
The word 馬脚 literally means a horse's legs, but it is normally used in the idiom.
In old plays, a performer called 馬脚 acted as the horse's hind legs.