gallows tree vs gallows-tree

gallows tree and gallows-tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
gallows tree	Yes	No	No	No
gallows-tree	Yes	No	No	No

As nouns, gallows tree and gallows-tree are synonyms defined as:

Other synonyms of gallows tree include gallous, gibbet.

gallows tree (noun)	gallows-tree (noun)
alternative terms for gallows	alternative terms for gallows