- risque
- rictus
- riding habit
- rubbish
- ready_made
- russet
- rubber band
- reoviridae
- representative
- relace
- relation
- roll in the hay
- ravelling
- raveling
- remnant
- remainder
- repossession
- respiration
- reseau
- ringlet
- raynaud's sign
- rayon stocking
- ruckle
- rumple
- revet
- refuse heap
- rubbish heap
- ribes rubrum
- red currant
- redwood family
- rust fungus
- royal velvet plant
- reflective power
- relative frequency
- respiratory quotient
- relative humidity
- rating system
- ratiocinator
- ridiculousness
- rich
- rousing
- Rosaceae
- rue family
- rose family
- Raoulia
- Rudbeckia
- Rubia
- Rosmarinus
- Ratibida
- religious discourse