The Collaborative International Dictionary of English v.0.48:

Guinea \Guin"ea\ (g[i^]n"[-e]), n.
   1. A district on the west coast of Africa (formerly noted for
      its export of gold and slaves) after which the Guinea
      fowl, Guinea grass, Guinea peach, etc., are named.
      [1913 Webster]

   2. A gold coin of England current for twenty-one shillings
      sterling, or about five dollars, but not coined since the
      issue of sovereigns in 1817.
      [1913 Webster]

            The guinea, so called from the Guinea gold out of
            which it
            was first struck, was proclaimed in 1663, and to go
            for twenty shillings; but it never went for less
            than twenty-one shillings.            --Pinkerton.
      [1913 Webster]

   Guinea corn. (Bot.) See Durra.

   Guinea Current (Geog.), a current in the Atlantic Ocean
      setting southwardly into the Bay of Benin on the coast of
      Guinea.

   Guinea dropper one who cheats by dropping counterfeit
      guineas. [Obs.] --Gay.

   Guinea fowl, Guinea hen (Zool.), an African gallinaceous
      bird, of the genus Numida, allied to the pheasants. The
      common domesticated species (Numida meleagris), has a
      colored fleshy horn on each aide of the head, and is of a
      dark gray color, variegated with small white spots. The
      crested Guinea fowl (Numida cristata) is a finer
      species.

   Guinea grains (Bot.), grains of Paradise, or amomum. See
      Amomum.

   Guinea grass (Bot.), a tall strong forage grass (Panicum
      jumentorum) introduced. from Africa into the West Indies
      and Southern United States.

   Guinea-hen flower (Bot.), a liliaceous flower (Fritillaria
      Meleagris) with petals spotted like the feathers of the
      Guinea hen.

   Guinea peach. See under Peach.

   Guinea pepper (Bot.), the pods of the Xylopia aromatica,
      a tree of the order Anonace[ae], found in tropical West
      Africa. They are also sold under the name of Piper
      aethiopicum.

   Guinea plum (Bot.), the fruit of Parinarium excelsum, a
      large West African tree of the order Chrysobalane[ae],
      having a scarcely edible fruit somewhat resembling a plum,
      which is also called gray plum and rough-skin plum.

   Guinea worm (Zool.), a long and slender African nematoid
      worm (Filaria Medinensis) of a white color. It lives in
      the cellular tissue of man, beneath the skin, and produces
      painful sores.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pepper \Pep"per\ (p[e^]p"p[~e]r), n. [OE. peper, AS. pipor, L.
   piper, fr. Gr. pe`peri, pi`peri, akin to Skr. pippala,
   pippali.]
   1. A well-known, pungently aromatic condiment, the dried
      berry, either whole or powdered, of the Piper nigrum.
      [1913 Webster]

   Note: Common pepper, or black pepper, is made from the
         whole berry, dried just before maturity; white pepper
         is made from the ripe berry after the outer skin has
         been removed by maceration and friction. It has less of
         the peculiar properties of the plant than the black
         pepper. Pepper is used in medicine as a carminative
         stimulant.
         [1913 Webster]

   2. (Bot.) The plant which yields pepper, an East Indian woody
      climber (Piper nigrum), with ovate leaves and apetalous
      flowers in spikes opposite the leaves. The berries are red
      when ripe. Also, by extension, any one of the several
      hundred species of the genus Piper, widely dispersed
      throughout the tropical and subtropical regions of the
      earth.
      [1913 Webster]

   3. Any plant of the genus Capsicum (of the Solanaceae
      family, which are unrelated to Piper), and its fruit;
      red pepper; chili pepper; as, the bell pepper and the
      jalapeno pepper (both Capsicum annuum) and the
      habanero pepper (Capsicum chinense); . These contain
      varying levels of the substance capsaicin (C18H27O3N),
      which gives the peppers their hot taste. The habanero is
      about 25-50 times hotter than the jalapeno according to a
      scale developed by Wilbur Scoville in 1912. See also
      Capsicum and http://www.chili-pepper-plants.com/.
      [1913 Webster + PJC]

   Note: The term pepper has been extended to various other
         fruits and plants, more or less closely resembling the
         true pepper, esp. to the common varieties of
         Capsicum. See Capsicum, and the Phrases, below.
         [1913 Webster]

   African pepper, the Guinea pepper. See under Guinea.

   Cayenne pepper. See under Cayenne.

   Chinese pepper, the spicy berries of the Xanthoxylum
      piperitum, a species of prickly ash found in China and
      Japan.

   Guinea pepper. See under Guinea, and Capsicum.

   Jamaica pepper. See Allspice.

   Long pepper.
      (a) The spike of berries of Piper longum, an East Indian
          shrub.
      (b) The root of Piper methysticum (syn. Macropiper
          methysticum) of the family Piperaceae. See Kava.


   Malaguetta pepper, or Meleguetta pepper, the aromatic
      seeds of the Amomum Melegueta, an African plant of the
      Ginger family. They are sometimes used to flavor beer,
      etc., under the name of grains of Paradise.

   Red pepper. See Capsicum.

   Sweet pepper bush (Bot.), an American shrub (Clethra
      alnifolia), with racemes of fragrant white flowers; --
      called also white alder.

   Pepper box or Pepper caster, a small box or bottle, with
      a perforated lid, used for sprinkling ground pepper on
      food, etc.

   Pepper corn. See in the Vocabulary.

   Pepper elder (Bot.), a West Indian name of several plants
      of the Pepper family, species of Piper and Peperomia.


   Pepper moth (Zool.), a European moth (Biston betularia)
      having white wings covered with small black specks.

   Pepper pot, a mucilaginous soup or stew of vegetables and
      cassareep, much esteemed in the West Indies.

   Pepper root. (Bot.). See Coralwort.

   pepper sauce, a condiment for the table, made of small red
      peppers steeped in vinegar.

   Pepper tree (Bot.), an aromatic tree (Drimys axillaris)
      of the Magnolia family, common in New Zealand. See
      Peruvian mastic tree, under Mastic.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Guinea pepper
    n 1: West African plant bearing pungent peppery seeds [syn:
         grains of paradise, Guinea grains, Guinea pepper,
         melagueta pepper, Aframomum melegueta]
    2: tropical west African evergreen tree bearing pungent aromatic
       seeds used as a condiment and in folk medicine [syn: Guinea
       pepper, negro pepper, Xylopia aethiopica]