- a painful, involuntary cramp of an arm or leg muscle resulting from excessive muscular strain or a blow.
- US and Canadian informal muscle stiffness or cramp following strenuous athletic exercise
1887, sporting slang, origin obscure, probably from somebody’s long-forgotten lame racehorse. Charley horse seems to have been a name for a horse or a type of horse (perhaps especially a lame one) around that time.
- Localized pain or stiffness in a muscle following excessive muscular exertion or the contusion of a muscle.
Cramp or stiffness in a muscle, most often in the thigh, as in After working in the garden I frequently get a bad charley horse. First used in the 1880s among baseball players, the term was soon extended to more general use. Its true origin is disputed. Among the more likely theories proposed is that it alludes to the name of either a horse or an afflicted ball player who limped like one of the elderly draft horses formerly employed to drag the infield.