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. also, any weed which bears burs.-the thin ridge left by a tool in cutting or shaping metal. see burr, n., 2.-a ring of iron on a lance or spear. see burr, n., 4.-the lobe of the ear. see burr, n., 5.-the sweetbread.-a clinker; a partially vitrified brick.-a small circular saw.-a triangular chisel.-a drill with a serrated head larger than the shank; -- used by dentists.-the round knob of an antler next to a deer's head.-a prickly seed vessel. see bur, 1.-the thin edge or ridge left by a tool in cutting or shaping metal, as in turning, engraving, pressing, etc.; also, the rough neck left on a bullet in casting.-a thin flat piece of metal, formed from a sheet by punching; a small washer put on the end of a rivet before it is swaged down.-a broad iron ring on a tilting lance just below the gripe, to prevent the hand from slipping.-the lobe or lap of the ear.-a guttural pronounciation of the letter r, produced by trilling the extremity of the soft palate against the back part of the tongue; rotacism; -- often called the newcastle, northumberland, or tweedside, burr.-the knot at the bottom of an antler. see bur, n., 8.-to speak with burr; to make a hoarse or guttural murmur.