Английский Этимологический словарь - mere (adj.)

- c.1390, from O.Fr. mier "pure, entire," from L. merus "unmixed, pure, bare," used of wine, probably originally "clear, bright." Original sense of "nothing less than, absolute" (now only in vestiges such as mere folly) has existed for centuries alongside opposite sense of "nothing more than" (a mere dream).