The Collaborative International Dictionary
                    Flacker
                    
                        
                
                                                                    Flacker \Flack"er\, v. i. [OE. flakeren, fr. flacken to move
   quickly to and fro; cf. icel. flakka to rove about, AS.
   flacor fluttering, flying, G. flackern to flare, flicker.]
   To flutter, as a bird. [Prov. Eng.] 
--Grose.
Wiktionary
                    flacker
                    
                        
                
                                                                    vb. 1 to flutter as a bird 2 to flicker, quiver
Usage examples of "flacker".
Police helicopters flackered noisily overhead, warning drivers who felt unwell to try and pull off the highway.
Police helicopters flackered noisily overhead, warning drivers who felt unwell to try and pull off the highway.