to calm down /kɑm daʊn/ /kɑːm daʊn/
to soothe /suð/ /suːð/
to pacify /ˈpæsəˌfaɪ/ /ˈpæsɪfaɪ/
to placate /ˈpleɪkeɪt/ /pləˈkeɪt/
to appease /əˈpiz/ /əˈpiːz/