Source : Webster's Revised Unabridged Dictionary (1913)

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.