Dictionary.net

The law administered during the Revolutionary period by Charles Lynch, a Virginia planter, and his associates, to Tories and other British sympathizers. The victims were hung up by their thumbs until they shouted: "Liberty forever !" but were never killed. In later years and at the present time the term is applied to summary executions without trial and usually by mob violence. It is practiced largely in the West and South, lynch-law executions being, in the United States at large, about twice as numerous as legal ones.