资料来源 : Webster's Revised Unabridged Dictionary (1913)

Oak \Oak\ ([=o]k), n. [OE. oke, ok, ak, AS. [=a]c; akin to D.
   eik, G. eiche, OHG. eih, Icel. eik, Sw. ek, Dan. eeg.]
   1. (Bot.) Any tree or shrub of the genus {Quercus}. The oaks
      have alternate leaves, often variously lobed, and
      staminate flowers in catkins. The fruit is a smooth nut,
      called an {acorn}, which is more or less inclosed in a
      scaly involucre called the cup or cupule. There are now
      recognized about three hundred species, of which nearly
      fifty occur in the United States, the rest in Europe,
      Asia, and the other parts of North America, a very few
      barely reaching the northern parts of South America and
      Africa. Many of the oaks form forest trees of grand
      proportions and live many centuries. The wood is usually
      hard and tough, and provided with conspicuous medullary
      rays, forming the silver grain.

   2. The strong wood or timber of the oak.

   Note: Among the true oaks in America are:

   {Barren oak}, or

   {Black-jack}, {Q. nigra}.

   {Basket oak}, {Q. Michauxii}.

   {Black oak}, {Q. tinctoria}; -- called also {yellow} or
      {quercitron oak}.

   {Bur oak} (see under {Bur}.), {Q. macrocarpa}; -- called also
      {over-cup} or {mossy-cup oak}.

   {Chestnut oak}, {Q. Prinus} and {Q. densiflora}.

   {Chinquapin oak} (see under {Chinquapin}), {Q. prinoides}.

   {Coast live oak}, {Q. agrifolia}, of California; -- also
      called {enceno}.

   {Live oak} (see under {Live}), {Q. virens}, the best of all
      for shipbuilding; also, {Q. Chrysolepis}, of California.
      

   {Pin oak}. Same as {Swamp oak}.

   {Post oak}, {Q. obtusifolia}.

   {Red oak}, {Q. rubra}.

   {Scarlet oak}, {Q. coccinea}.

   {Scrub oak}, {Q. ilicifolia}, {Q. undulata}, etc.

   {Shingle oak}, {Q. imbricaria}.

   {Spanish oak}, {Q. falcata}.

   {Swamp Spanish oak}, or

   {Pin oak}, {Q. palustris}.

   {Swamp white oak}, {Q. bicolor}.

   {Water oak}, {Q. aguatica}.

   {Water white oak}, {Q. lyrata}.

   {Willow oak}, {Q. Phellos}. Among the true oaks in Europe
      are:

   {Bitter oak}, or

   {Turkey oak}, {Q. Cerris} (see {Cerris}).

   {Cork oak}, {Q. Suber}.

   {English white oak}, {Q. Robur}.

   {Evergreen oak},

   {Holly oak}, or

   {Holm oak}, {Q. Ilex}.

   {Kermes oak}, {Q. coccifera}.

   {Nutgall oak}, {Q. infectoria}.

   Note: Among plants called oak, but not of the genus
         {Quercus}, are:

   {African oak}, a valuable timber tree ({Oldfieldia
      Africana}).

   {Australian, or She}, {oak}, any tree of the genus
      {Casuarina} (see {Casuarina}).

   {Indian oak}, the teak tree (see {Teak}).

   {Jerusalem oak}. See under {Jerusalem}.

   {New Zealand oak}, a sapindaceous tree ({Alectryon
      excelsum}).

   {Poison oak}, the poison ivy. See under {Poison}.

Poison \Poi"son\, n. [F. poison, in Old French also, a potion,
   fr. L. potio a drink, draught, potion, a poisonous draught,
   fr. potare to drink. See {Potable}, and cf. {Potion}.]
   1. Any agent which, when introduced into the animal organism,
      is capable of producing a morbid, noxious, or deadly
      effect upon it; as, morphine is a deadly poison; the
      poison of pestilential diseases.

   2. That which taints or destroys moral purity or health; as,
      the poison of evil example; the poison of sin.

   {Poison ash}. (Bot.)
      (a) A tree of the genus {Amyris} ({A. balsamifera}) found
          in the West Indies, from the trunk of which a black
          liquor distills, supposed to have poisonous qualities.
      (b) The poison sumac ({Rhus venenata}). [U. S.]

   {Poison dogwood} (Bot.), poison sumac.

   {Poison fang} (Zo["o]l.), one of the superior maxillary teeth
      of some species of serpents, which, besides having the
      cavity for the pulp, is either perforated or grooved by a
      longitudinal canal, at the lower end of which the duct of
      the poison gland terminates. See Illust. under {Fang}.

   {Poison gland} (Biol.), a gland, in animals or plants, which
      secretes an acrid or venomous matter, that is conveyed
      along an organ capable of inflicting a wound.

   {Poison hemlock} (Bot.), a poisonous umbelliferous plant
      ({Conium maculatum}). See {Hemlock}.

   {Poison ivy} (Bot.), a poisonous climbing plant ({Rhus
      Toxicodendron}) of North America. It is common on stone
      walls and on the trunks of trees, and has trifoliate,
      rhombic-ovate, variously notched leaves. Many people are
      poisoned by it, if they touch the leaves. See {Poison
      sumac}. Called also {poison oak}, and {mercury}.

   {Poison nut}. (Bot.)
      (a) Nux vomica.
      (b) The tree which yields this seed ({Strychnos
          Nuxvomica}). It is found on the Malabar and Coromandel
          coasts.

   {Poison oak} (Bot.), the poison ivy; also, the more shrubby
      {Rhus diversiloba} of California and Oregon.

   {Poison sac}. (Zo["o]l.) Same as {Poison gland}, above. See
      Illust. under {Fang}.

   {Poison sumac} (Bot.), a poisonous shrub of the genus {Rhus}
      ({R. venenata}); -- also called {poison ash}, {poison
      dogwood}, and {poison elder}. It has pinnate leaves on
      graceful and slender common petioles, and usually grows in
      swampy places. Both this plant and the poison ivy ({Rhus
      Toxicodendron}) have clusters of smooth greenish white
      berries, while the red-fruited species of this genus are
      harmless. The tree ({Rhus vernicifera}) which yields the
      celebrated Japan lacquer is almost identical with the
      poison sumac, and is also very poisonous. The juice of the
      poison sumac also forms a lacquer similar to that of
      Japan.

   Syn: Venom; virus; bane; pest; malignity.

   Usage: {Poison}, {Venom}. Poison usually denotes something
          received into the system by the mouth, breath, etc.
          Venom is something discharged from animals and
          received by means of a wound, as by the bite or sting
          of serpents, scorpions, etc. Hence, venom specifically
          implies some malignity of nature or purpose.

资料来源 : WordNet®

poison oak
     n 1: dermatitis resulting from contact with a poison oak plant
     2: climbing plant common in eastern and central United States
        with ternate leaves and greenish flowers followed by white
        berries; yields an irritating oil that causes a rash on
        contact [syn: {poison ivy}, {markweed}, {poison mercury},
        {Toxicodendron radicans}, {Rhus radicans}]