1566, "an outlaw," specifically "one of a class of Irish robbers noted for outrages and savage cruelty," from Irish toruighe "plunderer," originally "pursuer, searcher," from Old Irish toirighim "I pursue," from toir "pursuit," from Celtic *to-wo-ret- "a running up to," from PIE root *ret- "to run, roll" (see rotary).
About 1646, it emerged as a derogatory term for Irish Catholics dispossessed of their land (some of whom subsequently turned to outlawry); c. 1680 applied by Exclusioners to supporters of the Catholic Duke of York (later James II) in his succession to the throne of England. After 1689, Tory was the name of a British political party at first composed of Yorkist Tories of 1680. Superseded c. 1830 by Conservative, though it continues to be used colloquially. As an adjective from 1680s. In American history, Tory was the name given after 1769 to colonists who remained loyal to the crown; it represents their relative position in the pre-revolutionary English political order in the colonies.
A Tory has been properly defined to be a traitor in thought, but not in deed. The only description, by which the laws have endeavoured to come at them, was that of non-jurors, or persons refusing to take the oath of fidelity to the state. [Jefferson, "Notes on the State of Virginia"]