0 bad, not useful, or not working:
He's directed so many movies that you might expect a few duff ones.
1 a person's bottom:
Get off your duff and start working.
Two days before I was due to have an appointment with the doctor, I found out I was up the duff.
There were continual rumours that the star was up the duff.
2 to steal farm animals by changing the brand (= owner's mark) on them, or to steal goods by changing their appearance
NOVÉ SLOVÁ
European
May 10, 2021
SLOVO DŇA
Shimmer
duff