bur

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

• noun A rough prickly husk or covering surrounding the seeds or fruits of plants such as the chestnut or the burdock.
• noun A plant producing such husks or coverings.
• noun A persistently clinging or nettlesome person or thing.
• noun A rough protuberance, especially a burl on a tree.
• noun Any of various rotary cutting tools designed to be attached to a drill.

from The Century Dictionary.

• noun The guttural pronunciation of the rough r common in some of the northern counties of England, especially Northumberland; rhotacism.
• noun A whirring noise. See birr, n.
• To speak with a guttural or rough pronunciation of the letter r.
• To talk or whisper hoarsely; murmur.
• To make a whirring noise. See birr, verb
• noun An abnormal outgrowth of wood, frequently of large size, occurring on the trunk or branch of a tree, usually as the result of some injury. See burl, 2.
• noun Same as burrow, 3.
• noun A halo round the moon. Compare burrow, 4, brough, 4.
• To extract (burs and other extraneous matter) from (wool) by chemical or mechanical means.
• To use a dental bur in the excavation of (a tooth-cavity).
• noun The native Indian name for the banian-tree.
• noun The rough, prickly case or covering of the seeds of certain plants, as of the chestnut and burdock.
• noun Hence The plant burdock: as, “rude burs and thistles,”
• noun In general, a protuberance upon, or a raised portion of, an object, usually more or less rough or irregular in form.
• noun The name of various tools and appliances.
• noun A partially vitrified brick; a clinker. Also called bur-brick.
• noun The blank driven out of a piece of sheet-metal by a punch.
• noun Waste raw silk.
• noun A name for the club-moss, Lycopodium clavatum.
• noun The sweetbread.
• noun Same as burl, 2.
• noun Same as burstone.
• noun The rounded knob forming the base of a deer's horn.
• noun The external meatus of the ear; the opening leading to the tympanum.

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

• noun (Bot.) Any rough or prickly envelope of the seeds of plants, whether a pericarp, a persistent calyx, or an involucre, as of the chestnut and burdock; a seed vessel having hooks or prickles. Also, any weed which bears burs.
• noun The thin ridge left by a tool in cutting or shaping metal. See Burr, n., 2.
• noun A ring of iron on a lance or spear. See Burr, n., 4.
• noun The lobe of the ear. See Burr, n., 5.
• noun The sweetbread.
• noun A clinker; a partially vitrified brick.
• noun A small circular saw.
• noun A triangular chisel.
• noun A drill with a serrated head larger than the shank; -- especially a small drill bit used by dentists.
• noun (Zoöl.) The round knob of an antler next to a deer's head.
• noun (Bot.) a useful and ornamental species of oak (Quercus macrocarpa) with ovoid acorns inclosed in deep cups imbricated with pointed scales. It grows in the Middle and Western United States, and its wood is tough, close-grained, and durable.
• noun (Bot.) a plant of the genus Sparganium, having long ribbonlike leaves.

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

• noun A rough, prickly husk around the seeds or fruit of some plants.
• noun Any of several plants having such husks.
• noun A rotary cutting implement having a selection of variously shaped heads.

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

• noun seed vessel having hooks or prickles
• verb remove the burrs from