rumination vs chewing

rumination and chewing both are nouns.

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

As nouns, chewing is a hypernym of rumination; that is, chewing is a word with a broader meaning than rumination:

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

Other hypernyms of rumination include chew, manduction, mastication.

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