bur, burr -- (seed vessel having hooks or prickles)
burr -- (rough projection left on a workpiece after drilling or cutting)
Burr, Aaron Burr -- (United States politician who served as vice president under Jefferson; he mortally wounded his political rival Alexander Hamilton in a duel and fled south (1756-1836))
burr -- (rotary file for smoothing rough edges left on a workpiece)
bur, burr -- (small bit used in dentistry or surgery)