The Collaborative International Dictionary of English v.0.48:

Lily \Lil"y\ (l[i^]l"[y^]), n.; pl. Lilies (l[i^]l"[i^]z).
   [AS. lilie, L. lilium, Gr. lei`rion. Cf. Flower-de-luce.]
   1. (Bot.) A plant and flower of the genus Lilium,
      endogenous bulbous plants, having a regular perianth of
      six colored pieces, six stamens, and a superior
      three-celled ovary.
      [1913 Webster]

   Note: There are nearly fifty species, all found in the North
         Temperate zone. Lilium candidum and Lilium
         longiflorum are the common white lilies of gardens;
         Lilium Philadelphicum is the wild red lily of the
         Atlantic States. Lilium Chalcedonicum is supposed to
         be the "lily of the field" in our Lord's parable;
         Lilium auratum is the great gold-banded lily of
         Japan.
         [1913 Webster]

   2. (Bot.) A name given to handsome flowering plants of
      several genera, having some resemblance in color or form
      to a true lily, as Pancratium, Crinum, Amaryllis,
      Nerine, etc.
      [1913 Webster]

   3. That end of a compass needle which should point to the
      north; -- so called as often ornamented with the figure of
      a lily or fleur-de-lis.
      [1913 Webster]

            But sailing further, it veers its lily to the west.
                                                  --Sir T.
                                                  Browne.
      [1913 Webster]

   4. (Auction Bridge) A royal spade; -- usually in pl. See
      Royal spade, below.
      [Webster 1913 Suppl.]

   African lily (Bot.), the blue-flowered Agapanthus
      umbellatus.

   Atamasco lily (Bot.), a plant of the genus Zephyranthes
      (Zephyranthes Atamasco), having a white and pink
      funnelform perianth, with six petal-like divisions
      resembling those of a lily. --Gray.

   Blackberry lily (Bot.), the Pardanthus Chinensis, the
      black seeds of which form a dense mass like a blackberry.


   Bourbon lily (Bot.), Lilium candidum. See Illust.

   Butterfly lily. (Bot.) Same as Mariposa lily, in the
      Vocabulary.

   Lily beetle (Zool.), a European beetle (Crioceris
      merdigera) which feeds upon the white lily.

   Lily daffodil (Bot.), a plant of the genus Narcissus, and
      its flower.

   Lily encrinite (Paleon.), a fossil encrinite, esp.
      Encrinus liliiformis. See Encrinite.

   Lily hyacinth (Bot.), a plant of the genus Hyacinthus.

   Lily iron, a kind of harpoon with a detachable head of
      peculiar shape, used in capturing swordfish.

   Lily of the valley (Bot.), a low perennial herb
      (Convallaria majalis), having a raceme of nodding,
      fragrant, white flowers.

   Lily pad, the large floating leaf of the water lily. [U.
      S.] --Lowell.

   Tiger lily (Bot.), Lilium tigrinum, the sepals of which
      are blotched with black.

   Turk's-cap lily (Bot.) Lilium Martagon, a red lily with
      recurved sepals; also, the similar American lily, Lilium
      superbum.

   Water lily (Bot.), the Nymph[ae]a, a plant with floating
      roundish leaves, and large flowers having many petals,
      usually white, but sometimes pink, red, blue, or yellow.
      [See Illust. of Nymph[ae]a.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

May \May\, n. [F. Mai, L. Maius; so named in honor of the
   goddess Maia (Gr. Mai^a), daughter of Atlas and mother of
   Mercury by Jupiter.]
   1. The fifth month of the year, containing thirty-one days.
      --Chaucer.
      [1913 Webster]

   2. The early part or springtime of life.
      [1913 Webster]

            His May of youth, and bloom of lustihood. --Shak.
      [1913 Webster]

   3. (Bot.) The flowers of the hawthorn; -- so called from
      their time of blossoming; also, the hawthorn.
      [1913 Webster]

            The palm and may make country houses gay. --Nash.
      [1913 Webster]

            Plumes that mocked the may.           --Tennyson.
      [1913 Webster]

   4. The merrymaking of May Day. --Tennyson.
      [1913 Webster]

   Italian may (Bot.), a shrubby species of Spiraea
      (Spiraea 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 (Zool.), 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 (Zool.), 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.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Convallamarin \Con*val`la*ma"rin\
   (k[o^]n*v[a^]l`l[.a]*m[=a]"r[i^]n), n. [Convallaria + L.
   amarus bitter.] (Chem.)
   A white, crystalline, poisonous substance, regarded as a
   glucoside, extracted from the lily of the valley
   (Convallaria Majalis). Its taste is first bitter, then
   sweet.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Convallaria majalis
    n 1: low-growing perennial plant having usually two large oblong
         lanceolate leaves and a raceme of small fragrant nodding
         bell-shaped flowers followed by scarlet berries [syn: lily
         of the valley, May lily, Convallaria majalis]