visual signal vs sock

visual signal and sock both are nouns.

Word	Noun	Adjective	Verb	Adverb
visual signal	Yes	No	No	No
sock	Yes	No	Yes	No

As nouns, sock is a hyponym of visual signal; that is, sock is a word with a more specific, narrower meaning than visual signal:

visual signal: a signal that involves visual communication
sock: a truncated cloth cone mounted on a mast; used (e.g., at airports) to show the direction of the wind

visual signal (noun)	sock (noun)
a signal that involves visual communication	hosiery consisting of a cloth covering for the foot; worn inside the shoe; reaches to between the ankle and the knee
	a truncated cloth cone mounted on a mast; used (e.g., at airports) to show the direction of the wind

visual signal (verb)	sock (verb)
	hit hard