howler monkey vs howler

howler monkey and howler both are nouns.

Word	Noun	Adjective	Verb	Adverb
howler monkey	Yes	No	No	No
howler	Yes	No	No	No

As nouns, howler monkey and howler are synonyms defined as:

howler monkey and howler: monkey of tropical South American forests having a loud howling cry

howler monkey (noun)	howler (noun)
monkey of tropical South American forests having a loud howling cry	a glaring blunder
	monkey of tropical South American forests having a loud howling cry
	a joke that seems extremely funny