flack1 / flak/ inf. • n. a publicity agent: a public relations flack.• v. [tr.] publicize or promote (something or someone): a crass ambulance-chaser who flacks himself in TV ads | [intr.] the local news media shamelessly flack for the organizing committee. DERIVATIVES: flack·er·y / -ərē/ n.flack2 • n. variant spelling of flak.