Alternative spelling of smoke signal

Alternative form of time signal

Alternative spelling of virtue signaller

Alternative spelling of danger signal.

(rail transport, UK) A small explosive charge (detonator) which can be placed on a railway line in fog, to be detonated by a train passing over it as a warning signal to the driver.

A traffic light.

a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day

A signal that only takes discrete values (contrasted to an analog signal that can take continuously varying values).

A signal that can vary in a continuous manner (as opposed to a digital signal that only takes discrete values).

(electrical engineering) The ratio comparing signal power to noise power. / (by extension) The quantity of quality information compared to irrelevant or incorrect information.