air sock vs visual signal

air sock and visual signal both are nouns.

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

As nouns, visual signal is a hypernym of air sock; that is, visual signal is a word with a broader meaning than air sock:

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

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