Word Study
orangeman
CIDE DICTIONARY
orangeman, n.
One of a secret society, organized in the north of Ireland in 1795, the professed objects of which are the defense of the reigning sovereign of Great Britain, the support of the Protestant religion, the maintenance of the laws of the kingdom, etc.; -- so called in honor of William, Prince of Orange , who became William III. of England. [1913 Webster]
OXFORD DICTIONARY
orangeman, n. (pl. -men) a member of a political society formed in 1795 to support Protestantism in Ireland.
Etymology
after William of Orange (William III)
For further exploring for "orangeman" in Webster Dictionary Online