football vs fullback

football and fullback both are nouns.

Word	Noun	Adjective	Verb	Adverb
football	Yes	No	No	No
fullback	Yes	No	Yes	No

football (noun)	fullback (noun)
any of various games played with a ball (round or oval) in which two teams try to kick or carry or propel the ball into each other's goal	(American football) the position of a back on a football team, generally larger in size than halfbacks
the inflated oblong ball used in playing American football	(football) the running back who plays the fullback position on the offensive team

football (verb)	fullback (verb)
	play the fullback