The Collaborative International Dictionary of English v.0.48:

Many \Ma"ny\, a. & pron.

   Note: [It has no variation to express degrees of comparison;
         more and most, which are used for the comparative and
         superlative degrees, are from a different root.] [OE.
         mani, moni, AS. manig, m[ae]nig, monig; akin to D.
         menig, OS. & OHG. manag, G. manch, Dan. mange, Sw.
         m[*a]nge, Goth. manags, OSlav. mnog', Russ. mnogii; cf.
         Icel. margr, Prov. E. mort. [root]103.]
   Consisting of a great number; numerous; not few.
   [1913 Webster]

         Thou shalt be a father of many nations.  --Gen. xvii.
                                                  4.
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         Not many wise men after the flesh, not many mighty, not
         many noble, are called.                  --1 Cor. i.
                                                  26.
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   Note: Many is freely prefixed to participles, forming
         compounds which need no special explanation; as,
         many-angled, many-celled, many-eyed, many-footed,
         many-handed, many-leaved, many-lettered, many-named,
         many-peopled, many-petaled, many-seeded, many-syllabled
         (polysyllabic), many-tongued, many-voiced, many-wived,
         and the like. In such usage it is equivalent to
         multi. Comparison is often expressed by many with as
         or so. "As many as were willing hearted . . . brought
         bracelets." --Exod. xxxv. 22. "So many laws argue so
         many sins." --Milton. Many stands with a singular
         substantive with a or an.
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   Many a, a large number taken distributively; each one of
      many. "For thy sake have I shed many a tear." --Shak.
      "Full many a gem of purest ray serene." --Gray.

   Many one, many a one; many persons. --Bk. of Com. Prayer.

   The many, the majority; -- opposed to the few. See
      Many, n.

   Too many, too numerous; hence, too powerful; as, they are
      too many for us. --L'Estrange.
      [1913 Webster]

   Syn: Numerous; multiplied; frequent; manifold; various;
        divers; sundry.
        [1913 Webster]

WordNet (r) 3.0 (2006):

many a
    adj 1: each of a large indefinite number; "many a man"; "many
           another day will come" [syn: many a(a), many an(a),
           many another(a)]