swan-neck vs swanneck

swan-neck and swanneck both are nouns.

Word	Noun	Adjective	Verb	Adverb
swan-neck	Yes	No	No	No
swanneck	Yes	No	No	No

As nouns, swan-neck and swanneck are synonyms defined as:

swan-neck and swanneck: any of several orchids of the genus Cycnoches having slender arching columns of flowers suggesting the neck of a swan

Other synonyms of swan-neck include swan-flower, swan orchid, swanflower.

swan-neck (noun)	swanneck (noun)
any of several orchids of the genus Cycnoches having slender arching columns of flowers suggesting the neck of a swan	any of several orchids of the genus Cycnoches having slender arching columns of flowers suggesting the neck of a swan