Source : Webster's Revised Unabridged Dictionary (1913)

Thistle \This"tle\, n. [OE. thistil, AS. [thorn]istel; akin to
   D. & G. distel, OHG. distila, distil, Icel. [thorn]istill,
   Sw. tistel, Dan. tidsel; of uncertain origin.] (Bot.)
   Any one of several prickly composite plants, especially those
   of the genera {Cnicus}, {Craduus}, and {Onopordon}. The name
   is often also applied to other prickly plants.

   {Blessed thistle}, {Carduus benedictus}, so named because it
      was formerly considered an antidote to the bite of
      venomous creatures.

   {Bull thistle}, {Cnicus lanceolatus}, the common large
      thistle of neglected pastures.

   {Canada thistle}, {Cnicus arvensis}, a native of Europe, but
      introduced into the United States from Canada.

   {Cotton thistle}, {Onopordon Acanthium}.

   {Fuller's thistle}, the teasel.

   {Globe thistle}, {Melon thistle}, etc. See under {Globe},
      {Melon}, etc.

   {Pine thistle}, {Atractylis gummifera}, a native of the
      Mediterranean region. A vicid gum resin flows from the
      involucre.

   {Scotch thistle}, either the cotton thistle, or the musk
      thistle, or the spear thistle; -- all used national
      emblems of Scotland.

   {Sow thistle}, {Sonchus oleraceus}.

   {Spear thistle}. Same as {Bull thistle}.

   {Star thistle}, a species of {Centaurea}. See {Centaurea}.

   {Torch thistle}, a candelabra-shaped plant of the genus
      Cereus. See {Cereus}.

   {Yellow thistle}, {Cincus horridulus}.

   {Thistle bird} (Zo["o]l.), the American goldfinch, or
      yellow-bird ({Spinus tristis}); -- so called on account of
      its feeding on the seeds of thistles. See Illust. under
      {Goldfinch}.

   {Thistle butterfly} (Zo["o]l.), a handsomely colored American
      butterfly ({Vanessa cardui}) whose larva feeds upon
      thistles; -- called also {painted lady}.

   {Thistle cock} (Zo["o]l.), the corn bunting ({Emberiza
      militaria}). [Prov. Eng.]

   {Thistle crown}, a gold coin of England of the reign of James
      I., worth four shillings.

   {Thistle finch} (Zo["o]l.), the goldfinch; -- so called from
      its fondness for thistle seeds. [Prov. Eng.]

   {Thistle funnel}, a funnel having a bulging body and flaring
      mouth.

Cotton \Cot"ton\ (k[o^]t"t'n), n. [F. coton, Sp. algodon the
   cotton plant and its wool, coton printed cotton, cloth, fr.
   Ar. qutun, alqutun, cotton wool. Cf. {Acton}, {Hacqueton}.]
   1. A soft, downy substance, resembling fine wool, consisting
      of the unicellular twisted hairs which grow on the seeds
      of the cotton plant. Long-staple cotton has a fiber
      sometimes almost two inches long; short-staple, from two
      thirds of an inch to an inch and a half.

   2. The cotton plant. See {Cotten plant}, below.

   3. Cloth made of cotton.

   Note: Cotton is used as an adjective before many nouns in a
         sense which commonly needs no explanation; as, cotton
         bagging; cotton cloth; cotton goods; cotton industry;
         cotton mill; cotton spinning; cotton tick.

   {Cotton cambric}. See {Cambric}, n., 2.

   {Cotton flannel}, the manufactures' name for a heavy cotton
      fabric, twilled, and with a long plush nap. In England it
      is called swan's-down cotton, or Canton flannel.

   {Cotton gin}, a machine to separate the seeds from cotton,
      invented by Eli Whitney.

   {Cotton grass} (Bot.), a genus of plants ({Eriphorum}) of the
      Sedge family, having delicate capillary bristles
      surrounding the fruit (seedlike achenia), which elongate
      at maturity and resemble tufts of cotton.

   {Cotton mouse} (Zool.), a field mouse ({Hesperomys
      gossypinus}), injurious to cotton crops.

   {Cotton plant} (Bot.), a plant of the genus {Gossypium}, of
      several species, all growing in warm climates, and bearing
      the cotton of commerce. The common species, originally
      Asiatic, is {G. herbaceum}.

   {Cotton press}, a building and machinery in which cotton
      bales are compressed into smaller bulk for shipment; a
      press for baling cotton.

   {Cotton rose} (Bot.), a genus of composite herbs ({Filago}),
      covered with a white substance resembling cotton.

   {Cotton scale} (Zo["o]l.), a species of bark louse
      ({Pulvinaria innumerabilis}), which does great damage to
      the cotton plant.

   {Cotton shrub}. Same as Cotton plant.

   {Cotton stainer} (Zo["o]l.), a species of hemipterous insect
      ({Dysdercus suturellus}), which seriously damages growing
      cotton by staining it; -- called also {redbug}.

   {Cotton thistle} (Bot.), the Scotch thistle. See under
      {Thistle}.

   {Cotton velvet}, velvet in which the warp and woof are both
      of cotton, and the pile is of silk; also, velvet made
      wholly of cotton.

   {Cotton waste}, the refuse of cotton mills.

   {Cotton wool}, cotton in its raw or woolly state.

   {Cotton worm} (Zool.), a lepidopterous insect ({Aletia
      argillacea}), which in the larval state does great damage
      to the cotton plant by eating the leaves. It also feeds on
      corn, etc., and hence is often called {corn worm}, and
      {Southern army worm}.

Source : WordNet®

cotton thistle
     n : biennial Eurasian white hairy thistle having pale purple
         flowers; naturalized in North America [syn: {woolly
         thistle}, {Scotch thistle}, {Onopordum acanthium}, {Onopordon
         acanthium}]