Aggress \Ag*gress"\, v. i. [imp. & p. p. {Aggressed}; p. pr. & vb. n. {Aggressing}.] [L. aggressus, p. p. of aggredi to go to, approach; ad + gradi to step, go, gradus step: cf. OF. aggresser. See {Grade}.] To commit the first act of hostility or offense; to begin a quarrel or controversy; to make an attack; -- with on.