Source : Webster's Revised Unabridged Dictionary (1913)

Pepper \Pep"per\, n. [OE. peper, AS. pipor, L. piper, fr. Gr. ?,
   ?, akin to Skr. pippala, pippali.]
   1. A well-known, pungently aromatic condiment, the dried
      berry, either whole or powdered, of the {Piper nigrum}.

   Note: Common, 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.

   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.

   3. Any plant of the genus Capsicum, and its fruit; red
      pepper; as, the bell pepper.

   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.

   {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, or Macropiper, methysticum}. See
          {Kava}.

   {Malaguetta}, 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 {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} (Zo["o]l.), 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}.

Cayenne \Cay*enne\, n. [From Cayenne, a town and island in
   French Guiana, South America.]
   Cayenne pepper.

   {Cayenne pepper}.
   (a) (Bot.) A species of {Capsicum} ({C. frutescens}) with
       small and intensely pungent fruit.
   (b) A very pungent spice made by drying and grinding the
       fruits or seeds of several species of the genus
       {Capsicum}, esp. {C. annuum} and {C. Frutescens}; --
       called also {red pepper}. It is used chiefly as a
       condiment.

Source : WordNet®

cayenne pepper
     n 1: plant bearing very hot and finely tapering long peppers;
          usually red [syn: {cayenne}, {chili pepper}, {chilli
          pepper}, {long pepper}, {jalapeno}, {Capsicum annuum
          longum}]
     2: ground pods and seeds of pungent red peppers of the genus
        Capsicum [syn: {cayenne}, {red pepper}]
     3: a long and often twisted hot red pepper [syn: {cayenne}]