noun
Formal term used in official contexts such as police reports, station lost-and-found, and public announcements.
駅の遺失物取扱所で遺失品を探した。
I looked for my lost item at the station's lost-and-found office.
遺失品が見つかったら、こちらにご連絡ください。
If your lost article is found, please contact us here.
Compound of 遺失 (loss, from 遺 'leave behind' and 失 'lose') and 品 (article, goods).