Here are some synonyms for the word "non-aggressive":
1. Peaceful - promoting or characterized by peace; not violent or warlike.
2. Mild - not severe or harsh; gentle or moderate in nature or effect.
3. Passive - accepting or allowing what happens or what others do, without active response or resistance.
4. Calm - without excitement or disturbance; free from mental or emotional agitation.
5. Non-combative - not inclined or disposed to fight or engage in warfare.
6. Submissive - ready to conform to the authority or will of others; meekly obedient or passive.
7. Pacifistic - promoting or advocating peace; characterized by opposition to war or violence.
8. Unaggressive - not combative or given to fighting or aggression.
9. Amicable - characterized by friendliness and goodwill; showing a pleasant and cooperative attitude.