(biochemistry, genetics) A key regulator of animal development present in many organisms from flies to humans.

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

A traffic light.

An indication that something is a paraphrase or direct quote. / A phrase that signals a particular meaning or stance.

plural of signal phrase

A gang sign.

plural of analog signal

plural of digital signal

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).