flak

noun4

1. •
   Ground-based anti-aircraft guns firing explosive shells.

   • Another peculiar modern development is that of […] military abbreviations in army orders such as Flak ('Fliegerabwehrkanone' or 'archie')[.] — 1931
2. •
   (informal, figurative) Adverse criticism.

   • Alex McLeish, perhaps mindful of the flak he has been taking from sections of the Villa support for a perceived negative style of play, handed starts to wingers Charles N'Zogbia and Albrighton. — 2011
3. •
   Anti-aircraft shell fire.

   • At 1057 we were just over the islands and at 1100 the tail gunner reported flak at six o'clock, below. — 1943
4. •
   (informal) A public-relations spokesperson.