burr

Burr is a term with several distinct meanings in botany, machining, and onomastics. It can refer to a prickly seed case on certain plants, a rough edge left on metal or plastic after a cutting operation, or be used as a surname. The different senses are unrelated aside from describing protruding or clingy forms.

In botany, a burr (also bur) is a seed capsule or fruit bearing one or more hooked or bristly structures that attach to fur, clothing, or feathers. This adaptation aids seed dispersal by hitching rides with animals or people. Common examples include burdock (Arctium) and cocklebur (Xanthium). Burrs can be a nuisance when they cling to clothing or fur.

In machining and metalworking, a burr is a raised edge or ridged fragment that remains on a workpiece after a cutting, drilling, or shaping operation. Burrs can be sharp or rounded and may interfere with assembly or function. They are typically removed by deburring, filing, grinding, or other finishing processes. The formation of a burr depends on cutting conditions, material properties, and tool geometry.

People with Burr as a surname include Aaron Burr (1756–1804), an American lawyer and politician who served as the third Vice President of the United States. He is best known for the Burr–Hamilton duel and for his controversial Western exploration. The surname is found in various regions and has multiple bearers in history and contemporary life.