mere (adj.) Look up mere at Dictionary.com
c.1400, "unmixed, pure," from Old French mier "pure" (of gold), "entire, total, complete," and directly from Latin merus "unmixed" (of wine), "pure; bare, naked;" figuratively "true, real, genuine," probably originally "clear, bright," from PIE *mer- "to gleam, glimmer, sparkle" (cognates: Old English amerian "to purify," Old Irish emer "not clear," Sanskrit maricih "ray, beam," Greek marmarein "to gleam, glimmer"). Original sense of "nothing less than, absolute" (mid-15c., now only in vestiges such as mere folly) existed for centuries alongside opposite sense of "nothing more than" (1580s, as in a mere dream).
mere (n.) Look up mere at Dictionary.com
Old English mere "sea, ocean; lake, pool, pond, cistern," from Proto-Germanic *mari (cognates: Old Norse marr, Old Saxon meri "sea," Middle Dutch maer, Dutch meer "lake, sea, pool," Old High German mari, German Meer "sea," Gothic marei "sea," mari-saiws "lake"), from PIE *mori- "sea" (cognates: Latin mare, Old Church Slavonic morje, Russian more, Lithuanian mares, Old Irish muir, Welsh mor "sea," Gaulish Are-morici "people living near the sea").