a whistling (action); whistle (sound); various hissing noises such as produced by a gush of wind, a diving bird or an air-piercing arrow (see sifflant).; noises produced by certain animals resembling a whistling, said of snakes, marmots, or cats.
to whistle; to whistle for, to blow on a whistle for; to boo by whistling (to show one's disapproval at something); to hiss; to knock back (a drink), to down