1. What does it mean?
팬미 abbreviates 팬미팅. It is an organized event focused on meeting and entertaining fans, which may include conversation, games, and performances. Compared with a concert, the emphasis can be more on interaction than a full musical set.
Also written or said as 팬미팅, paenmi
2. The nuance
Formats vary. The name does not guarantee personal one-to-one time, a handshake, or an autograph; those depend on the announced program.
3. Examples
“이번 팬미는 토크 코너가 특히 재밌었어.”
The talk segment was especially fun at this fan meeting.
“팬미 일정이 떠서 달력에 표시했어.”
The fan meeting date was announced, so I marked my calendar.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.