weather vane vs weathervane

weather vane and weathervane both are nouns.

Word	Noun	Adjective	Verb	Adverb
weather vane	Yes	No	No	No
weathervane	Yes	No	No	No

As nouns, weather vane and weathervane are synonyms defined as:

weather vane and weathervane: mechanical device attached to an elevated structure; rotates freely to show the direction of the wind

Other synonyms of weather vane include vane, wind vane.

weather vane (noun)	weathervane (noun)
mechanical device attached to an elevated structure; rotates freely to show the direction of the wind	mechanical device attached to an elevated structure; rotates freely to show the direction of the wind