Father-in-law; the father of one's spouse (essentially synonymous with '義父'). Often referred to in speech as 'お義父さん'.
彼の舅はとても優しい人だ。
His father-in-law is a very kind person.
結婚してから舅と同居することになった。
After getting married, we ended up living with my father-in-law.
妻は舅に毎週料理を持って行っている。
My wife brings food to her father-in-law every week.