- a movement or sound made by someone that has a special meaning to another person
- a fact, event or action that shows what someone intends to do or shows what is likely to happen
- pictures, sound or other information sent by one piece of electronic equipment and received by another one
Origin and usage
The origin of the word signal comes from Late Middle English via Old French and the medieval Latin ‘signale’, the neuter of the Late Latin ‘signalis’, which was derived from the Latin ‘signum’ meaning a mark or token. The usage of signal in modern English encompasses many distinct varieties of signals, with one of the more recent developments including electronic and digital communications.
While the first meaning of the word signal above includes almost any kind of expression that has a specific meaning between two parties, the development of this word has grown to mean an assortment of communication transmission types.
Telecommunication, for example, falls under the third definition of the word signal as it encompasses the science of transmitting information through electromagnets. Analogue versions of telecommunication methods that were most popular in the 19th and 20th centuries for providing services such as radio and television are frequently being replaced by digital conversion methods, which change the type of signal that is used in communicating the information or images.
“We know what molecules are needed to sense light – what turns that signal that detects light into an electrical signal. We know how smells are detected. But we have a vast number of senses for which we know what the signal is, but we don’t know what the receiver is…”
“Distinguishing the signal from the noise requires both scientific knowledge and self-knowledge.”
sign, gesture, indication