ground rule vs ball

ground rule and ball both are nouns.

Word	Noun	Adjective	Verb	Adverb
ground rule	Yes	No	No	No
ball	Yes	No	Yes	No

ground rule (noun)	ball (noun)
(baseball) a special rule (as in baseball) dealing with situations that arise due to the nature of the playing grounds	a pitch that is not in the strike zone
	a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs
	round object that is hit or thrown or kicked in games
	a spherical object used as a plaything
	a solid projectile that is shot by a musket
	a more or less rounded anatomical body or mass
	one of the two male reproductive glands that produce spermatozoa and secrete androgens
	a lavish dance requiring formal attire
	a compact mass
	an object with a spherical shape

ground rule (verb)	ball (verb)
	form into a ball by winding or rolling
	to live very well