\Rough"rid`er\, n.
An officer or enlisted man in the 1st U. S. Volunteer
Cavalry, a regiment raised for the Spanish war of 1898,
composed mostly of Western cowboys and hunters and Eastern
college athletes and sportsmen, largely organized, and later
commanded, by Theodore Roosevelt. Sometimes, locally, a
member of any of various volunteer cavalry commands raised in
1898. [Colloq.]

\Rough"rid`er\, n.
One who breaks horses; especially (Mil.), a noncommissioned
officer in the British cavalry, whose duty is to assist the
riding master.