Loss
noun, verbal noun
The thing we leave behind at a fault is a loss.
いしつ
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
この空港に遺失物取扱所があるかどうかをご存知ですか。
Do you know if there is a lost and found office in this airport?