A curve with equation rθ = k in polar coordinates. The figure shows the curve obtained when k = 1.
A hyperbolic spiral
- Akatsuki
- Akbar, Jalaludin Muhammad (1542–1605)
- Akebono
- Akers, Thomas Dale (1951– )
- Akhenaten (14th century bc)
- akinete
- Akiyama, Toyohiro (1942– )
- Akkad
- aklé
- akolasia
- akoluthic
- akrasia
- Aksayan
- Aksum
- aktuopalaeontology
- al-
- alabaster
- Alamein, El, Battle of (October–November 1942)
- Alamo, the
- Alanbrooke, Alan Francis Brooke, 1st Viscount (1883–1963)
- alanine
- Alan Turing Institute
- alar
- ALARA
- Alaric I (c.370–410)