1. Signe. Un signal de reconnaissance.
2. Panneau. Un signal pour la circulation.
3. Information. Un signal extrait du bruit de fond.
4. (Au figuré) Départ. Le signal d'un changement.
Any sign, gesture, sound, or action that conveys information.
Examples include the use of flags (semaphore), light (traffic and railroad signals), radio telephony, radio telegraphy (Morse code), and electricity (telecommunications and computer networks).
The International Code of Signals used by shipping was drawn up by an international committee and published 1931. The codes and abbreviations used by aircraft are dealt with by the International Civil Aviation Organization, established 1944.
An electrical transmittance (either input or output) that conveys information.