Source : Webster's Revised Unabridged Dictionary (1913)

Pearl \Pearl\, n. [OE. perle, F. perle, LL. perla, perula,
   probably fr. (assumed) L. pirulo, dim. of L. pirum a pear.
   See {Pear}, and cf. {Purl} to mantle.]
   1. (Zo["o]l.) A shelly concretion, usually rounded, and
      having a brilliant luster, with varying tints, found in
      the mantle, or between the mantle and shell, of certain
      bivalve mollusks, especially in the pearl oysters and
      river mussels, and sometimes in certain univalves. It is
      usually due to a secretion of shelly substance around some
      irritating foreign particle. Its substance is the same as
      nacre, or mother-of-pearl. Pearls which are round, or
      nearly round, and of fine luster, are highly esteemed as
      jewels, and compare in value with the precious stones.

   2. Hence, figuratively, something resembling a pearl;
      something very precious.

            I see thee compassed with thy kingdom's pearl.
                                                  --Shak.

            And those pearls of dew she wears.    --Milton.

   3. Nacre, or mother-of-pearl.

   4. (Zo["o]l.) A fish allied to the turbot; the brill.

   5. (Zo["o]l.) A light-colored tern.

   6. (Zo["o]l.) One of the circle of tubercles which form the
      bur on a deer's antler.

   7. A whitish speck or film on the eye. [Obs.] --Milton.

   8. A capsule of gelatin or similar substance containing some
      liquid for medicinal application, as ether.

   9. (Print.) A size of type, between agate and diamond. [hand]
      This line is printed in the type called pearl.

   {Ground pearl}. (Zo["o]l.) See under {Ground}.

   {Pearl barley}, kernels of barley, ground so as to form
      small, round grains.

   {Pearl diver}, one who dives for pearl oysters.

   {Pearl edge}, an edge of small loops on the side of some
      kinds of ribbon; also, a narrow kind of thread edging to
      be sewed on lace.

   {Pearl eye}, cataract. [R.]

   {Pearl gray}, a very pale and delicate blue-gray color.

   {Pearl millet}, Egyptian millet ({Penicillaria spicata}).

   {Pearl moss}. See {Carrageen}.

   {Pearl moth} (Zo["o]l.), any moth of the genus {Margaritia};
      -- so called on account of its pearly color.

   {Pearl oyster} (Zo["o]l.), any one of several species of
      large tropical marine bivalve mollusks of the genus
      {Meleagrina}, or {Margaritifera}, found in the East Indies
      (especially at Ceylon), in the Persian Gulf, on the coast
      of Australia, and on the Pacific coast of America. Called
      also {pearl shell}, and {pearl mussel}.

   {Pearl powder}. See {Pearl white}, below.

   {Pearl sago}, sago in the form of small pearly grains.

   {Pearl sinter} (Min.), fiorite.

   {Pearl spar} (Min.), a crystallized variety of dolomite,
      having a pearly luster.

   {Pearl white}.
      (a) Basic bismuth nitrate, or bismuth subchloride; -- used
          chiefly as a cosmetic.
      (b) A variety of white lead blued with indigo or Berlin
          blue.