WordNet (r) 3.0 (2006):

flack
    n 1: a slick spokesperson who can turn any criticism to the
         advantage of their employer [syn: flak catcher, flak,
         flack catcher, flack]
    2: intense adverse criticism; "Clinton directed his fire at the
       Republican Party"; "the government has come under attack";
       "don't give me any flak" [syn: fire, attack, flak,
       flack, blast]
    3: artillery designed to shoot upward at airplanes [syn:
       antiaircraft, antiaircraft gun, flak, flack, pom-
       pom, ack-ack, ack-ack gun]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "flack":
   advocacy, advocating, antiaircraft fire, bruiting, buildup,
   cross fire, curtain fire, direct fire, drumbeating, dry fire,
   file fire, fire, fire of demolition, firepower, fireworks, firing,
   flak, ground fire, gunfight, gunfire, gunplay, high-angle fire,
   horizontal fire, interdiction fire, machine-gun fire, mortar fire,
   musketry, percussion fire, pistol fire, promoting, promotion,
   publicization, publicizing, raking fire, rapid fire, ricochet fire,
   rifle fire, shellfire, shoot-out, shooting, time fire,
   vertical fire, zone fire