Off duty; not scheduled for work or on-call — commonly used in workplaces with shift or duty rotations (e.g., police, hospitals).
今日は非番だから家でゆっくり休むつもりだ。
I'm off duty today, so I plan to rest at home.
非番の警官が事故の処理を手伝った。
An off-duty police officer helped handle the accident.
非番でも緊急の連絡には対応してください。
Please respond to emergency contact even when you're off duty.