noun
outsider; person outside a group
Refers to someone who does not belong to a particular organization, circle, or category. Often used in contexts like company security, confidential information, or exclusive events.
この会議には部外者の参加は認められていません。
Outsiders are not allowed to attend this meeting.
部外者に社内の情報を漏らしてはいけない。
You must not leak internal company information to outsiders.
よそ者 is a more colloquial and sometimes negative term for an outsider or stranger, often implying someone from a different region or community, whereas 部外者 is neutral and focuses on group membership.
Compound of 部 (ぶ, 'section, department, group') + 外 (がい, 'outside') + 者 (しゃ, 'person'). Literally 'person outside the group'.