"washing, purification," 1610s, from Late Latin elutionem (nominative elutio) "a washing out," noun of action from past participle stem of Latin eluere "to wash out, wash off, clean," from ex- "out" (see ex-) + luere "to wash" (see lave). Especially in reference to a process of obtaining sugar from molasses.[elution etymology, elution origin, 英语词源]