Etymology
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calm (v.)
late 14c., "to become calm," from Old French calmer or from calm (adj.). Also transitive, "to make still or quiet" (1550s). Related: Calmed; calming.
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sedation (n.)

early 15c., "alleviation of pain;" 1540s, "act of making calm," from French sédation and directly from Latin sedationem (nominative sedatio) "a quieting, assuaging, a calming," noun of action from past-participle stem of sedare (see sedate (adj.)).

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sedative (adj.)
"tending to calm or soothe," early 15c., from Medieval Latin sedativus "calming, allaying," from sedat-, past participle stem of sedare, causative of sedere "to sit," from PIE root *sed- (1) "to sit." The noun derivative meaning "a sedative drug" is attested from 1785. Hence, "whatever soothes or allays."
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appeasement (n.)

mid-15c., appesement, "pacification," from Old French apaisement "appeasement, calming," noun of action from apaisier "pacify, make peace, placate" (see appease). First recorded 1919 in international political sense; not pejorative until the failure of British Prime Minister Neville Chamberlain's policy toward Germany in 1939 (methods of appeasement was Chamberlain's description of his policy).

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