big vs animal

big is not a noun while animal is a noun.

Word	Noun	Adjective	Verb	Adverb
big	No	Yes	No	Yes
animal	Yes	Yes	No	No

big (noun)	animal (noun)
	a living organism characterized by voluntary movement

big (adjective)	animal (adjective)
above average in size or number or quantity or magnitude or extent	marked by the appetites and passions of the body
conspicuous in position or importance
given or giving freely
generous and understanding and tolerant
marked by intense physical force
significant
prodigious
serious or severe
loud and firm
(of animals) fully developed
in an advanced stage of pregnancy
feeling self-importance
exhibiting self-importance