- reduction factor
- reduction ratio
- reductive agent
- redundant constraint
- redundant structure
- redundants
- redwood
- reed roofing
- reedle vibrator
- reef
- reel carriage
- reeled paper
- reeling
- reengineering
- reeving
- refectory
- reference
- reference drawing
- reference ellipsoid
- reference label
- reference level
- reference line
- reference manual
- reference peg
- reference point
- reference style
- refined bitumen
- refined lake
- refinery
- refitting repair
- reflected radiation
- reflected sound
- reflecting concrete
- reflecting material
- reflecting microscope
- reflecting sign
- reflecting surface
- reflection paper
- reflective paper
- reflector
- reflux valve
- refracting medium
- refractory aggregate
- refractory ceramics
- refractory lime
- refractory putty
- refractory timber
- refreshment room
- refrigerating post
- refrigeration store
- refuge
- refuge island
- refuge siding
- refusal gauge
- refuse
- refuse collector
- refuse tip
- regardless
- regelation
- regenerate
- regeneration
- regenerative heating
- regenerator
- regime
- regiment
- region
- regional center
- regional highway
- regional planning
- recycling
- red rot
- red spot
- redox potential
- redraft
- reduced eccentricity
- reduced load
- reduced power
- reduced span
- reduced stiffness
- reduced stress
- reduced visibility
- reducing bend
- reducing cross
- reducing elbow
- reduction
- reduction data
- reduction elements
- reduction-oxidation
- redundancy
- redundant
- redundant bar
- redundant member
- redundant support
- reed
- reed mat
- reed roof
- reel
- reference mark
- reference network
- reference plane