Longman Dictionary of Contemporary English
parents-in-law
noun
EXAMPLES FROM CORPUS
▪ A new bride is expected to cover her head in the presence of her parents-in-law and older brothers-in-law.
▪ I think I made it once for my parents-in-law.
▪ Seven A few years previously, Melissa had been in the Cévennes on a motoring holiday with her parents-in-law.
▪ This materialism also means that the traditional tyrants, the parents-in-law, are being increasingly regarded by married couples as burdens.
▪ When I spoke about this problem to my parents-in-law they only laughed.
▪ Whether she does this or not depends, in Britain, on her own personality and on the attitude of her parents-in-law.
Wiktionary
parents-in-law
n. (parent-in-law English)
Usage examples of "parents-in-law".
He was probably just dropping her a friendly note, the way parents-in-law do.