eff /ef/ BrE AmE verb [intransitive] British English spoken informal
[ Date: 1900-2000 ; Origin: f , the first letter of fuck ]
1 . effing and blinding swearing:
Did you hear her effing and blinding at him?
2 . eff off! used to tell someone to go away instead of saying ↑ fuck off
⇨ ↑ effing