burr1

[bur] /bɜr/
noun
1.
Also, buhr. a protruding, ragged edge raised on the surface of metal during drilling, shearing, punching, or engraving.
2.
a rough or irregular protuberance on any object, as on a tree.
3.
a small, hand-held, power-driven milling cutter, used by machinists and die makers for deepening, widening, or undercutting small recesses.
4.
a lump of brick fused or warped in firing.
verb (used with object)
5.
to form a rough point or edge on.
6.
deburr.
Also, bur (for defs 1, 3).
Origin
1605-15; spelling variant of bur1

burr2

[bur] /bɜr/
noun
1.
a washer placed at the head of a rivet.
2.
a blank punched out of a piece of sheet metal.
Also, bur.
Origin
1375-1425; late Middle English burrewez (plural), buruhe circle, variant of brough round tower; see broch

burr3

[bur] /bɜr/
noun
1.
a pronunciation of the r- sound as a uvular trill, as in certain Northern English dialects.
2.
a pronunciation of the r- sound as an alveolar flap or trill, as in Scottish English.
3.
any pronunciation popularly considered rough or nonurban.
4.
a whirring noise.
verb (used without object)
5.
to speak with a burr.
6.
to speak roughly, indistinctly, or inarticulately.
7.
to make a whirring sound.
verb (used with object)
8.
to pronounce (words, sounds, etc.) with a burr.
Origin
1750-60; apparently both imitative and associative, the sound being thought of as rough like a bur

burr4

[bur] /bɜr/
noun
1.
burstone.
Also, buhr.
Origin
1250-1300; Middle English burre, probably so called from its roughness

Burr

[bur] /bɜr/
noun
1.
Aaron, 1756–1836, vice president of the U.S. 1801–05.
Examples from the web for burr
  • The bridge has a single span, wooden, double burr arch trusses design.
  • The sixth station, also on the electric line, is a half mile north on burr oak ave.
  • The acquisition of the entire parcel bounded by burr oak ave.
British Dictionary definitions for burr

burr1

/bɜː/
noun
1.
a small power-driven hand-operated rotary file, esp for removing burrs or for machining recesses
2.
a rough edge left on a workpiece after cutting, drilling, etc
3.
a rough or irregular protuberance, such as a burl on a tree
4.
(Brit) a burl on the trunk or root of a tree, sliced across for use as decorative veneer
noun, verb
5.
a variant spelling of bur
verb (transitive)
6.
to form a rough edge on (a workpiece)
7.
to remove burrs from (a workpiece) by grinding, filing, etc; deburr
Word Origin
C14: variant of bur

burr2

/bɜː/
noun
1.
(phonetics) an articulation of (r) characteristic of certain English dialects, esp the uvular fricative trill of Northumberland or the retroflex r of the West of England
2.
a whirring sound
verb
3.
to pronounce (words) with a burr
4.
to make a whirring sound
Word Origin
C18: either special use of bur (in the sense: rough sound) or of imitative origin

burr3

/bɜː/
noun
1.
a washer fitting around the end of a rivet
2.
a blank punched out of sheet metal
Word Origin
C16 (in the sense: broad ring on a spear): variant of burrow (in obsolete sense: borough)

burr4

/bɜː/
noun
1.
short for buhrstone
2.
a mass of hard siliceous rock surrounded by softer rock
Word Origin
C18: probably from bur, from its qualities of roughness

Burr

/bɜː/
noun
1.
Aaron. 1756–1836, US vice-president (1800–04), who fled after killing a political rival in a duel and plotted to create an independent empire in the western US; acquitted (1807) of treason
Word Origin and History for burr
n.

"rough sound of the letter -r-" (especially that common in Northumberland), 1760, later extended to "northern accented speech" in general. Possibly the sound of the word is imitative of the speech peculiarity itself, or it was adapted from one of the senses of bur (q.v.), perhaps from the phrase to have a bur in (one's) throat (late 14c.), which was a figure of speech for "feel a choking sensation, huskiness." OED says the Scottish -r- is a lingual trill, not a true burr.

burr in Medicine

burr (bûr)
n.
Variant of bur.

burr in Science
bur also burr
  (bûr)   
A type of pseudocarp in which the outer surface possesses hooks or barbs. Burs become caught in the feathers or hair of animals, which then carry them away to disperse the seeds.