Aggressor
Pronunciation : Ag*gres"sor
Part of Speech : n.
Etymology : [L.: cf. F. agresseur.]
Definition : Defn: The person who first attacks or makes an aggression; he who begins hostility or a quarrel; an assailant. The insolence of the aggressor is usually proportioned to the tameness of the sufferer. Ames.
Source : Webster's Unabridged Dictionary, 1913