"M8" is a common slang term in Australia and the UK, meaning "mate" or "friend." It is likely used in Prince William in the same way, as a friendly and casual way to address someone.
Examples:
- "Hey M8, how's it going?"
- "Cheers M8, see you later."
While "M8" is a widely understood term, it might not be appropriate in all situations, especially formal ones.
