Noah Webster's Dictionary (n.) The person who first attacks or makes an aggression; he who begins hostility or a quarrel; an assailant.

Multi-Version Concordance Aggressor (2 Occurrences) 1 Timothy 1:13 although I was before a blasphemer, a persecutor, and insolent. However, I obtained mercy, because I did it ignorantly in unbelief. (See NAS) Isaiah 16:4 Let those who have been forced out of Moab have a resting-place with you; be a cover to them from him who is making waste their land: till the cruel ones are cut off, and wasting has come to an end, and those who take pleasure in crushing the poor are gone from the land. (See NIV)