/flak/ , n.
1. antiaircraft fire, esp. as experienced by the crews of combat airplanes at which the fire is directed.
2. criticism; hostile reaction; abuse: Such an unpopular decision is bound to draw a lot of flak from the press.
Also, flack .
[ 1935-40; Fl ( ieger ) a ( bwehr ) k ( anone ) antiaircraft gun, equiv. to Flieger aircraft (lit., flyer) + Abwehr defense + Kanone gun, CANNON ]