I. goof 1 /ɡuːf/ BrE AmE ( also goof up ) verb [intransitive and transitive]
especially American English informal to make a silly mistake:
Somebody goofed and entered the wrong amount.
The restaurant totally goofed up our reservations.
goof around phrasal verb American English informal
to spend time doing silly things or not doing very much SYN mess about British English :
We spent the afternoon just goofing around on our bikes.
goof off phrasal verb American English informal
to waste time or avoid doing any work:
He’s been goofing off at school.
II. goof 2 BrE AmE noun [countable] especially American English informal
[ Date: 1900-2000 ; Origin: Probably from goff 'stupid person' (16-20 centuries) , from French goffe 'awkward, stupid' ]
1 . ( also goof up ) a silly mistake:
The goof could cost the city $5 million.
2 . ( also goofball ) someone who is silly