chew vs rumination

chew and rumination both are nouns.

Word	Noun	Adjective	Verb	Adverb
chew	Yes	No	Yes	No
rumination	Yes	No	No	No

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

chew: biting and grinding food in your mouth so it becomes soft enough to swallow
rumination: (of ruminants) chewing (the cud)

Other hyponyms of chew include chomping, gumming, mumbling.

chew (noun)	rumination (noun)
biting and grinding food in your mouth so it becomes soft enough to swallow	regurgitation of small amounts of food; seen in some infants after feeding
a wad of something chewable as tobacco	(of ruminants) chewing (the cud)
	a calm, lengthy, intent consideration

chew (verb)	rumination (verb)
chew (food); to bite and grind with the teeth