- Breaker / break
- Request to join or interrupt a conversation; also a CB operator.
- Copy / good copy
- I understand / signal is clear.
- Handle
- On-air nickname (not a legal callsign).
- 10-4
- Acknowledgement (from older 10-codes; still heard casually).
- On the side
- Standing by / listening on the channel.
- Negatory
- No.
- Roger
- Message received.
- Over
- End of my transmission; your turn (less used on casual channels).
- Out
- Finished and leaving the channel.
- XYL / YL
- Wife / young lady (traditional radio slang; use respectfully).
- QSY
- Change frequency (borrowed from amateur Q-codes).
- 73
- Best regards (amateur tradition; sometimes heard elsewhere).
For licence rules and etiquette see the UK guides and UK CB pages. Always follow Ofcom rules for your service.