1A member of a secret society formed in Ireland in 1843 in order to resist evictions from land for the non-payment of rent.
2A member of a union of mineworkers said to have been responsible for strikes and acts of violence and sabotage in the coalfields of Pennsylvania and West Virginia between 1862 and 1876. Also in plural, with the: the organization itself.
The union was made up chiefly of Irish immigrants belonging to the Ancient Order of Hibernians, a secret fraternal society. There seems to have been no connection between them and the Irish agitators; the term Molly Maguires was used by mine owners and other authorities in an attempt to discredit the unionists, rather than by the unionists of themselves.
Mid 19th century; earliest use found in Freeman's Journal. Probably from the name of Molly Maguire, supposed Irish widow said to have led or inspired the Irish activists of the 1840s, though compare quots. 1868 at sense 1 and 1908 at sense 1, and compare molly.