radi - reac
- radiactive
- radial
- radial component
- radial deflecting electrode
- radial disclination
- radial doppler
- radial field
- radial grating
- radial injection
- radial lead
- radial mode
- radial mode number
- radial photometer
- radial tracking
- radial transmission line
- radial wave
- radial-beam tube
- radial-discharge laser
- radial-lead capacitor
- radial-lead component
- radial-lead resistor
- radian
- radian frequency
- radiance
- radiance temperature
- radiancy
- radianlength
- radiansphere
- radiant
- radiant density
- radiant emittance
- radiant energy
- radiant exitance
- radiant exposure
- radiant flux
- radiant flux density
- radiant gain
- radiant heating
- radiant intensity
- radiant sensitivity
