Black's Law Dictionary, Sixth Edition, p. 1570

violence.  Unjust or unwarranted exercise of force, usually with accompaniment of vehemence, outrage, or fury.  People v. McIlvain, 55 Cal.App.2d 322, 130 P.2d 131, 134.  Physical force unlawfully exercised; abuse of force; that force which is employed against common right, against the laws, and against public liberty.  Anderson-Berney Bldg. Co. v. Lowry, Tex.Civ.App., 143 S.W.2d 401, 403.  The exertion of any physical force so as to injure, damage or abuse.  See e.g. Assault.

Violence in labor disputes is not limited to physical contact or injury, but may include picketing conducted with misleading signs, false statements, publicity, and veiled threats by words and acts.  Esco Operating Corporation v. Kaplan, 144 Misc. 646, 258 N.Y.S. 303.  

[Black's Law Dictionary, Sixth Edition, p. 1570]