IPA: /pləˈkeɪtə/
KK: /pləˈkeɪtər/
A person who calms someone down or makes them feel better, especially after a disagreement or conflict.
The placater spoke softly to ease the tension in the room.
Placater → It is formed from "placare" (meaning to calm or appease) and the suffix "-er" (meaning one who). The word "placater" refers to one who calms or appeases others.
Think of someone who 'calms' ('placare') others — that's why a placater is someone who helps to soothe or appease.