sos

• POS: Noun

CIDE DICTIONARY

sos,  

 The letters signified by the signal ( . . . --- . . . ) prescribed by the International Radiotelegraphic Convention of 1912 for use by ships in distress.  [Webster 1913 Suppl.]

OXFORD DICTIONARY

sos, n. (pl. SOSs)
1 an international code-signal of extreme distress, used esp. by ships at sea.
2 an urgent appeal for help.
3 Brit. a message broadcast to an untraceable person in an emergency.

Etymology

chosen as being easily transmitted and recognized in Morse code

THESAURUS

sos

Klaxon, Mayday, air-raid alarm, alarm, alarm bell, alarm clock, alarm signal, alarum, alert, all clear, beacon, blinking light, burglar alarm, buzzer, crostarie, fiery cross, fire alarm, fire bell, fire flag, five-minute gun, flashing light, fog bell, fog signal, foghorn, gale warning, hooter, horn, hue and cry, hurricane warning, lighthouse, note of alarm, occulting light, police whistle, signal of distress, siren, small-craft warning, still alarm, storm cone, storm flag, storm warning, tocsin, two-minute gun, upside-down flag, whistle