pacifist

Short definition from Wiktionary

Noun

1. 1
   One who loves, supports, or favours peace.
2. 2
   One who loves, supports, or favours peace: One who prefers to avoid violence in daily life.
3. 3
   One who loves, supports, or favours peace: One who is anti-war.
4. 4
   One who loves, supports, or favours peace: One who both abstains from inflicting violence on others and opposes others doing so.
5. 5
   A player who attempts the challenge of winning a game without attacking any enemy characters.

Adjective

1. 1
   Of or relating to pacifism; pacifistic.