1550s, from Middle French incommensurable or directly from Medieval Latin incommensurabilis, from in- "not, opposite of, without" (see in- (1)) + Late Latin commensurabilis, from Latin com- "with" + mensurabilis "measurable," from mensurare "to measure" (see measure (v.)). Related: Incommensurably.[incommensurable etymology, incommensurable origin, 英语词源]