What is "pearl oyster"

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. [1913 Webster] [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.

   1. Basic bismuth nitrate, or bismuth subchloride; -- used chiefly as a cosmetic.

   2. A variety of white lead blued with indigo or Berlin blue.

Oyster \Oys"ter\ (ois"t[~e]r), n. [OF. oistre, F. hu[^i]tre, L. ostrea, ostreum, Gr. 'o`streon; prob. akin to 'ostre`on bone, the oyster being so named from its shell. Cf. Osseous, Ostracize.]

1. (Zo["o]l.) Any marine bivalve mollusk of the genus Ostrea. They are usually found adhering to rocks or other fixed objects in shallow water along the seacoasts, or in brackish water in the mouth of rivers. The common European oyster ( Ostrea edulis), and the American oyster ( Ostrea Virginiana), are the most important species.

2. A name popularly given to the delicate morsel contained in a small cavity of the bone on each side of the lower part of the back of a fowl. Fresh-water oyster (Zo["o]l.), any species of the genus Etheria, and allied genera, found in rivers of Africa and South America. They are irregular in form, and attach themselves to rocks like oysters, but they have a pearly interior, and are allied to the fresh-water mussels. Oyster bed, a breeding place for oysters; a place in a tidal river or other water on or near the seashore, where oysters are deposited to grow and fatten for market. See 1st Scalp, n. Oyster catcher (Zo["o]l.), See oystercatcher in the vocabulary. Oyster crab (Zo["o]l.) a small crab ( Pinnotheres ostreum) which lives as a commensal in the gill cavity of the oyster. Oyster dredge, a rake or small dragnet for bringing up oysters from the bottom of the sea. Oyster fish. (Zo["o]l.)

   1. The tautog.

   2. The toadfish. Oyster plant. (Bot.)

      1. A plant of the genus Tragopogon ( Tragopogon porrifolius), the root of which, when cooked, somewhat resembles the oyster in taste; salsify; -- called also vegetable oyster.

      2. A plant found on the seacoast of Northern Europe, America and Asia ( Mertensia maritima), the fresh leaves of which have a strong flavor of oysters.

         Oyster plover. (Zo["o]l.) Same as oystercatcher.

         Oyster shell (Zo["o]l.), the shell of an oyster.

         Oyster wench, Oyster wife, Oyster women, a women who deals in oysters.

         Pearl oyster. (Zo["o]l.) See under Pearl.

         Thorny oyster (Zo["o]l.), any spiny marine shell of the genus Spondylus.

n. Any of several bivalve molluscs that are a source of pearls, but especially ''Pinctada margaritifera''

n. tropical marine bivalve found chiefly off eastern Asia and Pacific coast of North America and Central America; a major source of pearls [syn: Pinctada margaritifera]