The Collaborative International Dictionary of English v.0.48:

Pea \Pea\, n.; pl. Peas (p[=e]z) or Pease (p[=e]z). [OE.
   pese, fr. AS. pisa, or OF. peis, F. pois; both fr. L. pisum;
   cf. Gr. pi`sos, pi`son. The final s was misunderstood in
   English as a plural ending. Cf. Pease.]
   1. (Bot.) A plant, and its fruit, of the genus Pisum, of
      many varieties, much cultivated for food. It has a
      papilionaceous flower, and the pericarp is a legume,
      popularly called a pod.
      [1913 Webster]

   Note: When a definite number, more than one, is spoken of,
         the plural form peas is used; as, the pod contained
         nine peas; but, in a collective sense, the form pease
         is preferred; as, a bushel of pease; they had pease at
         dinner. This distinction is not always preserved, the
         form peas being used in both senses.
         [1913 Webster]

   2. A name given, especially in the Southern States, to the
      seed of several leguminous plants (species of Dolichos,
      Cicer, Abrus, etc.) esp. those having a scar (hilum)
      of a different color from the rest of the seed.
      [1913 Webster]

   Note: The name pea is given to many leguminous plants more or
         less closely related to the common pea. See the
         Phrases, below.
         [1913 Webster]

   Beach pea (Bot.), a seashore plant, Lathyrus maritimus.


   Black-eyed pea, a West Indian name for Dolichos
      sph[ae]rospermus and its seed.

   Butterfly pea, the American plant Clitoria Mariana,
      having showy blossoms.

   Chick pea. See Chick-pea.

   Egyptian pea. Same as Chick-pea.

   Everlasting pea. See under Everlasting.

   Glory pea. See under Glory, n.

   Hoary pea, any plant of the genus Tephrosia; goat's rue.


   Issue pea, Orris pea. (Med.) See under Issue, and
      Orris.

   Milk pea. (Bot.) See under Milk.

   Pea berry, a kind of a coffee bean or grain which grows
      single, and is round or pea-shaped; often used
      adjectively; as, pea-berry coffee.

   Pea bug. (Zool.) Same as Pea weevil.

   Pea coal, a size of coal smaller than nut coal.

   Pea crab (Zool.), any small crab of the genus
      Pinnotheres, living as a commensal in bivalves; esp.,
      the European species (Pinnotheres pisum) which lives in
      the common mussel and the cockle.

   Pea dove (Zool.), the American ground dove.

   Pea-flower tribe (Bot.), a suborder (Papilionace[ae]) of
      leguminous plants having blossoms essentially like that of
      the pea. --G. Bentham.

   Pea maggot (Zool.), the larva of a European moth (Tortrix
      pisi), which is very destructive to peas.

   Pea ore (Min.), argillaceous oxide of iron, occurring in
      round grains of a size of a pea; pisolitic ore.

   Pea starch, the starch or flour of the common pea, which is
      sometimes used in adulterating wheat flour, pepper, etc.


   Pea tree (Bot.), the name of several leguminous shrubs of
      the genus Caragana, natives of Siberia and China.

   Pea vine. (Bot.)
      (a) Any plant which bears peas.
      (b) A kind of vetch or tare, common in the United States
          (Lathyrus Americana, and other similar species).

   Pea weevil (Zool.), a small weevil (Bruchus pisi) which
      destroys peas by eating out the interior.

   Pigeon pea. (Bot.) See Pigeon pea.

   Sweet pea (Bot.), the annual plant Lathyrus odoratus;
      also, its many-colored, sweet-scented blossoms.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sweet \Sweet\, a. [Compar. Sweeter; superl. Sweetest.] [OE.
   swete, swote, sote, AS. sw[=e]te; akin to OFries. sw[=e]te,
   OS. sw[=o]ti, D. zoet, G. s["u]ss, OHG. suozi, Icel. saetr,
   soetr, Sw. s["o]t, Dan. s["o]d, Goth. suts, L. suavis, for
   suadvis, Gr. ?, Skr. sv[=a]du sweet, svad, sv[=a]d, to
   sweeten. [root]175. Cf. Assuage, Suave, Suasion.]
   1. Having an agreeable taste or flavor such as that of sugar;
      saccharine; -- opposed to sour and bitter; as, a sweet
      beverage; sweet fruits; sweet oranges.
      [1913 Webster]

   2. Pleasing to the smell; fragrant; redolent; balmy; as, a
      sweet rose; sweet odor; sweet incense.
      [1913 Webster]

            The breath of these flowers is sweet to me.
                                                  --Longfellow.
      [1913 Webster]

   3. Pleasing to the ear; soft; melodious; harmonious; as, the
      sweet notes of a flute or an organ; sweet music; a sweet
      voice; a sweet singer.
      [1913 Webster]

            To make his English sweet upon his tongue.
                                                  --Chaucer.
      [1913 Webster]

            A voice sweet, tremulous, but powerful. --Hawthorne.
      [1913 Webster]

   4. Pleasing to the eye; beautiful; mild and attractive; fair;
      as, a sweet face; a sweet color or complexion.
      [1913 Webster]

            Sweet interchange
            Of hill and valley, rivers, woods, and plains.
                                                  --Milton.
      [1913 Webster]

   5. Fresh; not salt or brackish; as, sweet water. --Bacon.
      [1913 Webster]

   6. Not changed from a sound or wholesome state. Specifically:
      (a) Not sour; as, sweet milk or bread.
      (b) Not state; not putrescent or putrid; not rancid; as,
          sweet butter; sweet meat or fish.
          [1913 Webster]

   7. Plaesing to the mind; mild; gentle; calm; amiable;
      winning; presuasive; as, sweet manners.
      [1913 Webster]

            Canst thou bind the sweet influence of Pleiades?
                                                  --Job xxxviii.
                                                  31.
      [1913 Webster]

            Mildness and sweet reasonableness is the one
            established rule of Christian working. --M. Arnold.
      [1913 Webster]

   Note: Sweet is often used in the formation of self-explaining
         compounds; as, sweet-blossomed, sweet-featured,
         sweet-smelling, sweet-tempered, sweet-toned, etc.
         [1913 Webster]

   Sweet alyssum. (Bot.) See Alyssum.

   Sweet apple. (Bot.)
      (a) Any apple of sweet flavor.
      (b) See Sweet-sop.

   Sweet bay. (Bot.)
      (a) The laurel (Laurus nobilis).
      (b) Swamp sassafras.

   Sweet calabash (Bot.), a plant of the genus Passiflora
      (Passiflora maliformis) growing in the West Indies, and
      producing a roundish, edible fruit, the size of an apple.


   Sweet cicely. (Bot.)
      (a) Either of the North American plants of the
          umbelliferous genus Osmorrhiza having aromatic roots
          and seeds, and white flowers. --Gray.
      (b) A plant of the genus Myrrhis (Myrrhis odorata)
          growing in England.

   Sweet calamus, or Sweet cane. (Bot.) Same as Sweet
      flag, below.

   Sweet Cistus (Bot.), an evergreen shrub (Cistus Ladanum)
      from which the gum ladanum is obtained.

   Sweet clover. (Bot.) See Melilot.

   Sweet coltsfoot (Bot.), a kind of butterbur (Petasites
      sagittata) found in Western North America.

   Sweet corn (Bot.), a variety of the maize of a sweet taste.
      See the Note under Corn.

   Sweet fern (Bot.), a small North American shrub (Comptonia
      asplenifolia syn. Myrica asplenifolia) having
      sweet-scented or aromatic leaves resembling fern leaves.


   Sweet flag (Bot.), an endogenous plant (Acorus Calamus)
      having long flaglike leaves and a rootstock of a pungent
      aromatic taste. It is found in wet places in Europe and
      America. See Calamus, 2.

   Sweet gale (Bot.), a shrub (Myrica Gale) having bitter
      fragrant leaves; -- also called sweet willow, and Dutch
      myrtle. See 5th Gale.

   Sweet grass (Bot.), holy, or Seneca, grass.

   Sweet gum (Bot.), an American tree (Liquidambar
      styraciflua). See Liquidambar.

   Sweet herbs, fragrant herbs cultivated for culinary
      purposes.

   Sweet John (Bot.), a variety of the sweet William.

   Sweet leaf (Bot.), horse sugar. See under Horse.

   Sweet marjoram. (Bot.) See Marjoram.

   Sweet marten (Zool.), the pine marten.

   Sweet maudlin (Bot.), a composite plant (Achillea
      Ageratum) allied to milfoil.

   Sweet oil, olive oil.

   Sweet pea. (Bot.) See under Pea.

   Sweet potato. (Bot.) See under Potato.

   Sweet rush (Bot.), sweet flag.

   Sweet spirits of niter (Med. Chem.) See Spirit of nitrous
      ether, under Spirit.

   Sweet sultan (Bot.), an annual composite plant (Centaurea
      moschata), also, the yellow-flowered (Centaurea
      odorata); -- called also sultan flower.

   Sweet tooth, an especial fondness for sweet things or for
      sweetmeats. [Colloq.]

   Sweet William.
      (a) (Bot.) A species of pink (Dianthus barbatus) of many
          varieties.
      (b) (Zool.) The willow warbler.
      (c) (Zool.) The European goldfinch; -- called also sweet
          Billy. [Prov. Eng.]

   Sweet willow (Bot.), sweet gale.

   Sweet wine. See Dry wine, under Dry.

   To be sweet on, to have a particular fondness for, or
      special interest in, as a young man for a young woman.
      [Colloq.] --Thackeray.
      [1913 Webster]

   Syn: Sugary; saccharine; dulcet; luscious.
        [1913 Webster]

WordNet (r) 3.0 (2006):

sweet pea
    n 1: climbing garden plant having fragrant pastel-colored
         flowers [syn: sweet pea, sweetpea, Lathyrus odoratus]