signal-n; 4 Senses

Sense Number 1: a nonverbal communication gesture

Commentary: SIGNAL[+event][+gesture][+communication][+nonverbal]

When the commander gives the signal, the soldiers will charge the hill.
John wasn't sure whether the woman at the next table was giving him signals or not.
The diver's signal for being out of air is a finger drawn across the throat.

PropBank: signal.01
WordNet 3.0 Sense Numbers: 1

Sense Number 2: an indication or evidence for a state of affairs, situation

Commentary: SIGNAL[+information][+role][+evidence][+for_state_of_affairs]

The weak credit markets were another signal of the troubled economy.
These yellow needles on your hemlock tree are a signal of stress.
The data give confusing signals about a discernible trend in temperature change.

PropBank: NM
WordNet 3.0 Sense Numbers: 2

Sense Number 3: an electromagnetic pulse or wave

Commentary: SIGNAL[+event][+pulse][+electromagnetic]

Radio signals travel at the speed of light.
The signal from the T.V. station is coming in loud and clear.
These relays boost the signal as it is carried over hundreds of miles.

PropBank: NM
WordNet 3.0 Sense Numbers: 3

Sense Number 4: a semaphore apparatus, a traffic light

Commentary: SIGNAL[+artifact][+apparatus][+light][+traffic]

John braked at the intersection as the traffic signal turned red.
The engineer saw the green signal ahead on the tracks, indicating it was safe to go.
Trains were delayed due to a malfunctioning signal along the commuter tracks.

PropBank: NM
WordNet 0.0 Sense Numbers: 1c