- flow built under a function
- real-time computer
- real-time control
- real-time operation system
- real-time system
- real unimodular group
- real unit
- real unitary space
- real valuation
- real value
- real-valued form
- real-valued function
- real-valued measurable cardinal
- real-valued series
- real variable
- real variety
- real vector
- real vector bundle
- real vector space
- real zero
- reanalysis
- rear
- rearrange
- rearrangeability
- rearrangeable