Synonyms for Peacemaker (same or very similar meaning)
WordNet sense 1 (someone who tries to bring peace):
conciliator, pacifier, make-peace, reconcilerWordNet sense 2 (a belt-fed machine gun capable of firing more than 500 rounds per minute; used by United States troops in World War II and the Korean War):
Browning machine gunFrom the ODE community, based on WordNetadd/edit