fathead vs cuckoo

fathead and cuckoo both are nouns.

Word	Noun	Adjective	Verb	Adverb
fathead	Yes	No	No	No
cuckoo	Yes	No	Yes	No

As nouns, fathead and cuckoo are synonyms defined as:

Other synonyms of fathead include bozo, goof, goofball, goose, jackass, twat, zany.

fathead (noun)	cuckoo (noun)
a man who is a stupid incompetent fool	any of numerous European and North American birds having pointed wings and a long tail
	a man who is a stupid incompetent fool

fathead (verb)	cuckoo (verb)
	repeat monotonously, like a cuckoo repeats his call