flak BrE AmE , flack /flæk/ noun [uncountable]
[ Date: 1900-2000 ; Language: German ; Origin: FLiegerAbwehrKanone 'flyer defence guns' ]
1 . informal strong criticism:
Lilley has taken a lot of flak for his views on drugs.
2 . bullets or ↑ shell s that are shot from the ground at enemy aircraft
⇨ ↑ flak jacket