thistle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of numerous often weedy plants of several genera of the composite family, including Cirsium, Carduus, and Onopordum, having prickly leaves and floral bracts.
• noun Any of various other prickly plants, such as Russian thistle.

from The Century Dictionary.

• noun One of numerous stout composite weeds, armed with spines or prickles, bearing globular or thickly cylindrical heads with purple, yellow, or white flowers and no rays, and dispersing their seed by the aid of a light globe of pappus.
• noun The artichoke.
• noun The wild lettuce, Lactuca Scariola, var. virosa.
• noun Same as blessed thistle.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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.
• noun Carduus benedictus, so named because it was formerly considered an antidote to the bite of venomous creatures.
• noun Cnicus lanceolatus, the common large thistle of neglected pastures.
• noun Cnicus arvensis, a native of Europe, but introduced into the United States from Canada.
• noun Onopordon Acanthium.
• noun the teasel.
• noun etc. See under Globe, Melon, etc.
• noun Atractylis gummifera, a native of the Mediterranean region. A vicid gum resin flows from the involucre.
• noun either the cotton thistle, or the musk thistle, or the spear thistle; -- all used national emblems of Scotland.
• noun Sonchus oleraceus.
• noun Same as Bull thistle.
• noun a species of Centaurea. See Centaurea.
• noun a candelabra-shaped plant of the genus Cereus. See Cereus.
• noun Cincus horridulus.
• noun (Zoöl.) the American goldfinch, or yellow-bird (Spinus tristis); -- so called on account of its feeding on the seeds of thistles. See Illust. under Goldfinch.
• noun (Zoöl.) a handsomely colored American butterfly (Vanessa cardui) whose larva feeds upon thistles; -- called also painted lady.
• noun (Zoöl.), [Prov. Eng.] the corn bunting (Emberiza militaria).
• noun a gold coin of England of the reign of James I., worth four shillings.
• noun (Zoöl.), [Prov. Eng.] the goldfinch; -- so called from its fondness for thistle seeds.
• noun a funnel having a bulging body and flaring mouth.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of several perennial composite plants, especially of genera Cirsium, Carduus, Cynara or Onopordum, having prickly leaves and showy flower heads with prickly bracts.
• noun This plant seen as the national emblem of Scotland.
• noun The Order of the Thistle, or membership thereof.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of numerous plants of the family Compositae and especially of the genera Carduus and Cirsium and Onopordum having prickly-edged leaves