What does it mean to appease someone?

To appease - to avoid conflict by giving in to the other side's demands, grievances. Note that since 1940 this Word, together with appeasement, has had a very negative sense indeed and has come to mean to give in to unreasonable demands made by a dictator. The policy of appeasing is associated above all with Neville Chamberlain and the Munich Agreement of Spetember 1938.