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lost property; something dropped and left behind
dropping something (without realising); losing something
落し物を届けに交番に行きました。
I went to the police box to turn in lost property.
落し物センターで財布を見つけた。
I found my wallet at the lost and found.
駅で落し物をしたので窓口に届け出た。
I lost something at the station, so I reported it at the window.