fool vs fathead

fool and fathead both are nouns.

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

As nouns, fathead is a hyponym of fool; that is, fathead is a word with a more specific, narrower meaning than fool:

fool (noun)	fathead (noun)
a person who lacks good judgment	a man who is a stupid incompetent fool
a person who is gullible and easy to take advantage of
a professional clown employed to entertain a king or nobleman in the Middle Ages

fool (verb)	fathead (verb)
indulge in horseplay
fool or hoax
spend frivolously and unwisely
make a fool or dupe of