also: せえ
fault; blame; because of; due to
Used in the pattern ...のせい (or ...せいで) to indicate that something is the cause of a negative result, often implying blame or responsibility. Can also be used more neutrally for cause-and-effect, but typically carries a negative nuance.
雨のせいで試合が中止になった。
The game was canceled because of the rain.
His failure is my fault.
I overslept because the train was late.
It's your fault that I was late.
I think it's because of the weather.