To calm; to bring peace to; to influence someone who was furious to the point that he or she becomes content or at least no longer irate
to bring from a state of angry or hostile feeling to one of patience or friendliness
If you placate someone, you do or say something to make them stop feeling angry. He smiled, trying to placate me `I didn't mean to upset you,' Agnew said in a placating voice. = appease. to make someone stop feeling angry = appease (past participle of placare)