Source : Webster's Revised Unabridged Dictionary (1913)

Burr \Burr\, v. i. [imp. & p. p. {Burred}; p. pr. & vb. n.
   {Burring}.]
   To speak with burr; to make a hoarse or guttural murmur.
   --Mrs. Browning.

Source : WordNet®

bur
     n 1: seed vessel having hooks or prickles [syn: {burr}]
     2: small bit used in dentistry or surgery [syn: {burr}]
     [also: {burring}, {burred}]

burred
     adj : having or covered with protective barbs or quills or spines
           or thorns or setae etc.; "a horse with a short bristly
           mane"; "bristly shrubs"; "burred fruits"; "setaceous
           whiskers" [syn: {barbed}, {barbellate}, {briary}, {briery},
            {bristled}, {bristly}, {burry}, {prickly}, {setose}, {setaceous},
            {spiny}, {thorny}]

bur
     v : remove the burrs from [syn: {burr}]
     [also: {burring}, {burred}]

burred
     See {bur}