late 14c., "a solving or being solved," from Old French solucion "division, dissolving; explanation; payment" or directly from Latin solutionem (nominative solutio) "a loosening or unfastening," noun of action from past participle stem of solvere "to loosen, untie, solve, dissolve" (see solve). Meaning "liquid containing a dissolved substance" is first recorded 1590s.[solution etymology, solution origin, 英语词源]