spread-eagle vs spreadeagle

spread-eagle is an adjective but spreadeagle is not an adjective.

Word	Noun	Adjective	Verb	Adverb
spread-eagle	No	Yes	Yes	No
spreadeagle	No	No	Yes	No

As verbs, spread-eagle and spreadeagle are synonyms defined as:

Other synonyms of spread-eagle include rout.

spread-eagle (adjective)	spreadeagle (adjective)
with arms and legs stretched out and apart

spread-eagle (verb)	spreadeagle (verb)
stretch out completely	defeat disastrously
defeat disastrously
stand with arms and legs spread out
execute a spread eagle on skates, with arms and legs stretched out
stretch over