noun
The ordinary sense: something is wrong, incorrect, or done by mistake. Common with particles such as 間違いがある, 間違いを直す, and 私の間違い.
この書類には漢字の間違いが三つある。
There are three kanji mistakes in this document.
That was my mistake.
noun
A less central use meaning an unfortunate happening or something going wrong, often in set-like phrasing such as 万一の間違い.
万一の間違いがあってからでは遅い。
If something goes wrong, it will be too late.
noun
indiscretion; improper conduct
Euphemistic and somewhat old-fashioned, especially for improper conduct or a sexual or romantic indiscretion between people.
二人の間に間違いがあったという噂が広まった。
Rumors spread that there had been an indiscretion between the two.