placate
v.v. to calm someone down or make them less angry. You use this when you want to stop a person from being upset or causing trouble.
v. to pacify or appease someone in order to prevent further anger or disturbance. Transitive — requires a direct object, typically a person or a group.
He gave her a gift to try to placate her.
The manager offered a full refund to placate the angry customer and prevent a negative review.
The diplomat's primary goal was to placate the regional tensions before the summit, ensuring that all parties felt their concerns had been heard and addressed.
First attested in the late 17ᵗʰ century; borrowed from Latin plācātus, perfect passive participle of plācō (“appease, placate”, literally “smooth, smoothen”) (see -ate (verb-forming suffix) and -ate (adjective-forming suffix) for more), ultimately thought to be from Proto-Indo-European plāk- (“smooth, flat”), from pele- (“broad, flat, plain”). Related to Latin placeō (“appease”), Old English flōh (“flat stone, chip”). More at please.