signal
UK: ˈsɪɡnəl | US: ˈsɪɡnəl
n. a gesture, action, or sound used to convey information or instructions
n. an electrical impulse or radio wave transmitted or received
vt. to transmit information or instructions by means of a signal
The word "signal" originates from the Latin signum (meaning "mark" or "sign"), which evolved into Old French signal as a noun meaning "a visible sign." The suffix -al was added to form a noun indicating the result or action related to the root. Over time, "signal" expanded from physical signs (e.g., flags, gestures) to include abstract transmissions (e.g., radio waves). The logic reflects a progression from concrete markers to broader communicative acts.
The referee raised his hand as a signal to stop the game.
The satellite sends a weak signal back to Earth.
She signaled her approval with a quick nod.
Traffic signals help regulate the flow of vehicles.
The sudden silence was a signal that something was wrong.