Forgotten Item, Something Forgotten, Forgotten Thing, Lost Property
noun
Remember how 忘れる is "to forget"? Well, a thing you've forgotten is a forgotten item.
わすれもの
You didn't learn this reading with the kanji 忘, but you did learn it with the vocabulary 忘れる. What was (わす) that reading again? You can't remember! It's become a forgotten item!
私は忘れ物が多い。
I forget things a lot.
これ、誰かの忘れ物じゃない？
Isn't this something someone forgot?
今日何か忘れ物をしたような気がするんだけど、それが何だったかをどうしても思い出せないんだよな。
I feel like I forgot something today, but I just can’t remember what it is.