merlin vs pigeon hawk

merlin and pigeon hawk both are nouns.

Word	Noun	Adjective	Verb	Adverb
merlin	Yes	No	No	No
pigeon hawk	Yes	No	No	No

As nouns, merlin and pigeon hawk are synonyms defined as:

merlin and pigeon hawk: small falcon of Europe and America having dark plumage with black-barred tail; used in falconry

Other synonyms of merlin include Falco columbarius.

merlin (noun)	pigeon hawk (noun)
small falcon of Europe and America having dark plumage with black-barred tail; used in falconry	small falcon of Europe and America having dark plumage with black-barred tail; used in falconry