(figuratively, by extension of the previous sense) An emergency.
The dialing sequence used in the United States for calls for emergency assistance from police, fire, and ambulance services. Calls to 911 are routed to a public safety access point (PSAP). Enhanced 911 (E911) provides caller location information to the PSAP. See also E911 and PSAP. 2001: A Space Odyssey The movie script was written by Arthur C. Clarke and Stanley Kubrick, and based on Clarke's short story "The Sentinel." In telecommunications circles, Clarke is better known as the inventor of communications satellites. He publicly unveiled the concept in an article entitled "ExtraTerrestrial Relays: Can Rocket Stations Give World-wide Radio Coverage," published in Wireless World in February 1945. See also Clarke, Sir Arthur C.