O.E. mænan "to mean, tell, say, complain," from W.Gmc. *mainijanan (cf. O.Fris. mena, Du. menen, Ger. meinen to think, suppose, be of the opinion"), from PIE *meino- "opinion, intent" (cf. O.C.S. meniti "to think, have an opinion," O.Ir. mian "wish, desire," Welsh mwyn "enjoyment"), probably from base *men- "think." Meaningful first attested 1852.
"low-quality," O.E. gemæne "common, public, general, universal, shared by all," from P.Gmc. *ga-mainiz "possessed jointly" (cf. O.Fris. mene, M.L.G. gemeine, Du. gemeen, Ger. gemein, Goth. gamains "common"), from PIE *ko-moin-i- "held in common," a compound adjective formed from collective prefix *ko- "together" (P.Gmc. *ga-) + *moi-n-, suffixed form of PIE base *mei- "to change, exchange" (see mutable); cf. second element in common, a word whose sense evolution parallels that of mean (adj.). Sense influenced by mean (n.). Meaning "inferior, poor" emerged c.1300; that of "stingy, nasty" first recorded 1665; weaker sense of "disobliging, pettily offensive" is from 1839, originally Amer.Eng. slang. Inverted sense of "remarkably good" (i.e. plays a mean saxophone) first recorded c.1900, also in phrase no mean _______ "not inferior" (1596, also, "not average," reflecting further confusion with mean (n.)). Meanie "cruel person" is from 1927.
"that which is halfway between extremes," early 14c., from O.Fr. meien, from L. medianus "of or that is in the middle" (see median). Oldest sense is musical. Sense of "so-so, mediocre" led to confusion with mean (adj.). First record of means "course of action," is late 14c.; sense of "wealth" is first recorded c.1600. This is the mean in meantime (mid-14c.), meanwhile (mid-15c.), and by no means (late 15c.).