- real place
- real point
- real power compact space
- real quadratic form
- real quadratic form
- real quadratic form of same class
- real radical of an ideal
- real representation of Lie group
- real root of Kac-Moody algebra
- real spectrum
- real symmetric matrix
- realtime computable function
- realtime computation
- real-time photogrammetry
- real valuation
- real variable
- real variety
- real vector bundle
- rearrangement function
- rearrangement of series
- rear view
- reason behaviour axiom
- reasonin by analogy
- reason maintenance system
- recession cone