Source : Webster's Revised Unabridged Dictionary (1913)

May \May\, v. [imp. {Might}] [AS. pres. m[ae]g I am able, pret.
   meahte, mihte; akin to D. mogen, G. m["o]gen, OHG. mugan,
   magan, Icel. mega, Goth. magan, Russ. moche. ?. Cf. {Dismay},
   {Main} strength, {Might}. The old imp. mought is obsolete,
   except as a provincial word.]
   An auxiliary verb qualifyng the meaning of another verb, by
   expressing:
   (a) Ability, competency, or possibility; -- now oftener
       expressed by can.

             How may a man, said he, with idle speech, Be won to
             spoil the castle of his health !     --Spenser.

             For what he [the king] may do is of two kinds; what
             he may do as just, and what he may do as possible.
                                                  --Bacon.

             For of all sad words of tongue or pen The saddest
             are these: ``It might have been.''   --Whittier.
   (b) Liberty; permission; allowance.

             Thou mayst be no longer steward.     --Luke xvi. 2.
   (c) Contingency or liability; possibility or probability.

             Though what he learns he speaks, and may advance
             Some general maxims, or be right by chance. --Pope.
   (d) Modesty, courtesy, or concession, or a desire to soften a
       question or remark.

             How old may Phillis be, you ask.     --Prior.
   (e) Desire or wish, as in prayer, imprecation, benediction,
       and the like. ``May you live happily.'' --Dryden.

   {May be}, & {It may be}, are used as equivalent to possibly,
      perhaps, by chance, peradventure. See 1st {Maybe}.

May \May\, n. [Cf. Icel. m[ae]r, Goth. mawi; akin to E. maiden.
   ?.]
   A maiden. [Obs.] --Chaucer.

May \May\, n. [F. Mai, L. Maius; so named in honor of the
   goddess Maia (Gr. ?), daughter of Atlas and mother of Mercury
   by Jupiter.]
   1. The fifth month of the year, containing thirty-one days.
      --Chaucer.

   2. The early part or springtime of life.

            His May of youth, and bloom of lustihood. --Shak.

   3. (Bot.) The flowers of the hawthorn; -- so called from
      their time of blossoming; also, the hawthorn.

            The palm and may make country houses gay. --Nash.

            Plumes that micked the may.           --Tennyson.

   4. The merrymaking of May Day. --Tennyson.

   {Italian may} (Bot.), a shrubby species of {Spir[ae]a} ({S.
      hypericifolia}) with many clusters of small white flowers
      along the slender branches.

   {May apple} (Bot.), the fruit of an American plant
      ({Podophyllum peltatum}). Also, the plant itself
      (popularly called {mandrake}), which has two lobed leaves,
      and bears a single egg-shaped fruit at the forking. The
      root and leaves, used in medicine, are powerfully drastic.
      

   {May beetle}, {May bug} (Zo["o]l.), any one of numerous
      species of large lamellicorn beetles that appear in the
      winged state in May. They belong to {Melolontha}, and
      allied genera. Called also {June beetle}.

   {May Day}, the first day of May; -- celebrated in the rustic
      parts of England by the crowning of a May queen with a
      garland, and by dancing about a May pole.

   {May dew}, the morning dew of the first day of May, to which
      magical properties were attributed.

   {May flower} (Bot.), a plant that flowers in May; also, its
      blossom. See {Mayflower}, in the vocabulary.

   {May fly} (Zo["o]l.), any species of {Ephemera}, and allied
      genera; -- so called because the mature flies of many
      species appear in May. See {Ephemeral fly}, under
      {Ephemeral}.

   {May game}, any May-day sport.

   {May lady}, the queen or lady of May, in old May games.

   {May lily} (Bot.), the lily of the valley ({Convallaria
      majalis}).

   {May pole}. See {Maypole} in the Vocabulary.

   {May queen}, a girl or young woman crowned queen in the
      sports of May Day.

   {May thorn}, the hawthorn.

Source : WordNet®

May
     n 1: the month following April and preceding June
     2: thorny Eurasian shrub of small tree having dense clusters of
        white to scarlet flowers followed by deep red berries;
        established as an escape in eastern North America [syn: {whitethorn},
         {English hawthorn}, {Crataegus laevigata}, {Crataegus
        oxycantha}]