Simplification

Etymonline dates simplification to the 1680s in English, borrowed from the French simplification, from simplifier, and records simplify from the 1650s, from the fifteenth-century French simplifier and Medieval Latin simplificare, formed from Latin simplex and facere, to make. Nothing in the sources fetched connects the word's arrival in English to chess, and no chess-specific coinage or first citation was found. Wikipedia's chess glossary defines simplification as a strategy of exchanging pieces, with several possible goals: as a defensive measure to reduce the size of an attacking force, to reduce the opponent's counterplay when holding an advantage, to try to obtain a draw, or as an attempt to gain an advantage by players strong in endgame play. The glossary gives liquidation as a synonym. Wikipedia's chess strategy article uses the verb in the sense of reducing material to reach an endgame.

First documented: n.a. for the chess sense; the English word dates from the 1680s per Etymonline — n.a. for the chess sense