buffalo soldier

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A member of one of the African-American regiments within the U.S. Army after the Civil War, serving primarily in the Indian wars of the late 1860s.

Wiktionary

1. n. US (military) (historical) An African-American soldier in the US Army, serving in one of a number of segregated units under white officers, in the period after the US Civil War up to the final racial integration of the US military, at the end of the Korean War.

GNU Webster's 1913

1. A black soldier of the United States army who served in the American west in the late 1800's, often as an indian fighter, and usually as part of an all-black troop; -- the name was given by the indians due to their their kinky hair, and the name was believed also to be a compliment on their courage.