all clear

from WordNet (r) 3.0 (2006)

all clear
    n 1: a signal (usually a siren) that danger is over
    2: permission to proceed because obstacles have been removed

from Moby Thesaurus II by Grady Ward, 1.0

52 Moby Thesaurus words for "all clear":
      Klaxon, Mayday, SOS, above water, air-raid alarm, alarm,
      alarm bell, alarm clock, alarm signal, alarum, alert, all straight,
      beacon, blinking light, burglar alarm, buzzer, clear, crostarie,
      fiery cross, fire alarm, fire bell, fire flag, five-minute gun,
      flashing light, fog bell, fog signal, foghorn, free and clear,
      gale warning, hooter, horn, hue and cry, hurricane warning,
      lighthouse, note of alarm, occulting light, out of debt,
      police whistle, signal of distress, siren, small-craft warning,
      solvent, still alarm, storm cone, storm flag, storm warning,
      tocsin, two-minute gun, unindebted, unowing, upside-down flag,
      whistle