noun
Often used in compound nouns such as 書き損じ (writing error) or 聞き損じ (mishearing). As a standalone noun, it refers to a mistake or failure, but it is more common in compounds.
書き損じの手紙を捨てた。
I threw away the letter with a writing mistake.
それは私の聞き損じだった。
That was my mishearing.