father-in-law
Pluralfathers-in-law
- 1The father of one's spouse.
At the reception, his father-in-law gave a warm and funny speech.
Her father-in-law had worked as a fisherman his whole life.
Oppositemother-in-law
Note
The plural is where this compound trips people up. The -s goes on father, giving fathers-in-law, because the fathers multiply, not the law. Father-in-laws is heard in casual speech but counts as nonstandard, so keep it out of careful writing. The phrase itself is old: Middle English already said fader in lawe, built the same way as the modern form.
- 2The husband of one's mother or father; a stepfather.
When her mother married again, the children gradually accepted their father-in-law into the household.
`Yes,` replied Snawley. `The fact is, I am not their father, Mr Squeers. I'm only their father-in-law.`
1839, Charles Dickens, Nicholas NicklebySimilarstepfather
Oppositestepmother
Note
An older use in which in-law could name a tie created by a parent's remarriage rather than one's own. Dickens's Nicholas Nickleby (1839) shows it plainly: Snawley insists he is not the children's father, "only their father-in-law." The sense is now dated, and a modern reader will hear a spouse's father instead, so say stepfather unless you are quoting or writing period dialogue.
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Origin
From Middle English fader in lawe (also fadyr-in-lay and fader yn lawe), equivalent to father plus the suffix -in-law.