A type of equatorial mounting consisting of two axes forming a T-shape, the upright being the polar axis and the bar the declination axis. The telescope is attached to one end of the declination axis, with a counterweight at the other. It is a popular design for mounting small telescopes. It was invented by J. von Fraunhofer.
- Buchan metamorphic zones
- Buchan spells
- Buchli, James Frederick (1945– )
- Buchmanism
- Buchner, Eduard
- Buchner funnel
- Buchner, Hans Ernst Angass
- bucket
- bucket-brigade device
- bucket sort
- Buckingham, George Villiers, 1st Duke of (1592–1628)
- Buckingham π theorem
- Buckland, William (1784–1856)
- buckle folding
- buckminsterfullerene
- buck-passing accounts
- buckyball
- buckytube
- bud
- Budarin, Nikolai Mikhailovich (1953– )
- Buddha
- Buddhism
- budding
- buddy system
- budgerigar