Burr or Bur may refer to:

• In certain species of plants, burr is a seed or dry fruit in which the seeds bear hooks or teeth which attach themselves to fur or clothing of passing animals or people. The hooks or teeth can be irritants. It is the inspiration for Velcro. Examples of plants that produce burrs include:
  • Burdock, various species of Arctium
  • Pirri-pirri Burr, various species of Acaena
  • Burr marigold, various species of Bidens
  • Cleavers or Stickywilly, Galium aparine
• In statistics the Burr distribution is a continuous probability distribution, usually defined by four parameters.
• In engineering, a burr refers to a deformation of metal wherin a raised edge forms on a metal part which has been machined.
• In metalworking (machining), burrs are small rotary cutters used in rotary tools.
• A burr puzzle is a type of interlocking mechanical puzzle.
• In wood, it is the British spelling of American burl.
• A burr is also any regional accent with French-type (uvular) "r" sound, e.g. the Northumberland burr. Words used to describe other accents include twang and drawl.
• Burr is also a common surname. See:
  • Aaron Burr
  • Raymond Burr
• Book title: Burr (novel) (about Aaron Burr).
• Burr or Borr is a god in Norse mythology.
• The Burs were a Germanic tribe in Dacia.