1. Having one barrel
   "most guns are single-barreled"
   - single-barrelled [US]

Antonym: double-barreled [US]

• riverside
• rivet
• rivet line
• riveter
• riveting
• riveting machine
• rivetter
• Riviera
• Rivina
• Rivina humilis
• rivulet
• rivulus
• Riyadh
• riyal
• riyal-omani
• rms
• Rn
• RNA
• RNA polymerase
• RNase
• RNIB
• RNLI
• Ro
• ro-ro
• roach