FIL
noun informal
A person’s father-in-law: my in-laws helped tremendously—my MIL prepared food and my FIL helped move boxes and furniture...
- I hope we can reschedule my FIL's long-awaited trip to see us.
- On my last trip to my in-laws' place, my FIL actually told me that I was disrespecting him by not wearing a bindi!
- D wanted to sleep in today, and since there will only be us and my FIL for dinner today and I could do this menu in my sleep, I said that was fine.
Origin
1960s: abbreviation.