- Archimedean semigroup
- Archimedean spiral
- Archimedean unit
- Archimedean vector lattice
- Archimedean vector lattice
- Archimedes law
- architectural drawing
- arc indexline chart
- arc in Rn
- arc length function
- arc length of a curve
- arc measurement
- arc-spline curve
- arc to chord correction
- arc-to-chord correction in Gauss projection
- Arcturus
- arcwise connected set
- area
- area
- area based image matching
- area coordinates
- area element
- area formula
- area formula of a circle
- area formula of a Lobachevskian triangle