1.
father-in-law
One's spouse's father.
義父は会社を経営している。
My father-in-law runs a company.
義父と一緒に釣りに行った。
I went fishing together with my father-in-law.
結婚して初めて義父に会った。
I met my father-in-law for the first time after getting married.
2.
stepfather
A man married to one's mother who is not one's biological father.
TERMS OF ADDRESS:
While 義父 is the formal/written term, in conversation people typically address their father-in-law as:
- お義父さん - most common
- 義のお父さん - explicit "in-law's father"
CONTEXT:
義父 is more commonly used in:
- Written documents
- Speaking about (not to) one's father-in-law
- Formal contexts
FAMILY TERMS WITH 義:
- 義母 - mother-in-law
- 義兄 - brother-in-law (older)
- 義弟 - brother-in-law (younger)
- 義姉 - sister-in-law (older)
- 義妹 - sister-in-law (younger)
NUANCE:
The 義 prefix indicates a family relationship through marriage rather than blood.