decision (n.)

mid-15c., "act of deciding," from Old French décision (14c.), from Latin decisionem (nominative decisio) "a decision, settlement, agreement," noun of action from past-participle stem of decidere "to decide, determine," literally "to cut off," from de "off" (see de-) + caedere "to cut" (from PIE root *kae-id- "to strike").

Meaning "final judgment or opinion in a case" is from 1550s. Meaning "quality of being decided in character, ability to make prompt determinations" is from 1781; sense of "a resolution, a fixing of purpose" is by 1886.  Decision-making (adjective) is recorded by 1946.