- ratchet
- rated range
- Rayleigh refractometer
- reaction matrix
- reactive
- reactivity ramp
- reactor cell
- reactor hall
- reagent
- receptor
- ram guard
- raman scattering
- rarefaction
- ratchet brace
- Rayleigh wave
- reaction force
- reactivate
- reactivity loss
- reactor accident
- reactor design
- reactor period
- reactor safety
- reactor wall
- read beam
- ream
- reciprocal transducer
- reciprocating force
- recombination coefficient
- recorded wavelength
- recording barometer
- recording characteristic
- recovery system
- rectifiable
- reactor tank
- reading lens
- receiver
- receiving assembly
- recharge time
- rechargeable cell
- reciprocal period
- recoil electron
- recoil nucleus
- recombination plant
- record changer
- rectification
- rectifier
- recycling time
- reduce
- rectify
- rectilinear motion
- reducer
- reduction mask
- reduction print
- reduction tube
- reference electrode
- reference reactor
- reference tone
- reffector
- reflected beam
- reflecting viewfinder
- reflex bunching
- reflex klystron
- reflux boiling
- refract
- refractiveness
- refractometer
- refrangible
- refrigeration thermodynamics
- refringency
- refusion
- recycle time
- redge wareguide
- reduced coordinates
- reduced variable
- reed switch
- reference input
- reflectance density
- reflecting screen
- reflecting telescope
- reflection method
- refracted light
- refraction
- refraction grating
- refraction method
- refractivity
- refractor
- refringence
- relaxtion
- reinduce
- relative abundance
- relative tone
- relay room
- release
- remanent
- remanent magnetization
- remanent state
- reference axis
- reference sound
- reffex
- reflect