ruminate vs cogitate

ruminate and cogitate both are verbs.

Word	Noun	Adjective	Verb	Adverb
ruminate	No	No	Yes	No
cogitate	No	No	Yes	No

As verbs, cogitate is a hypernym of ruminate; that is, cogitate is a word with a broader meaning than ruminate:

ruminate: reflect deeply on a subject
cogitate: use or exercise the mind or one's power of reason in order to make inferences, decisions, or arrive at a solution or judgments

Other hypernyms of ruminate include cerebrate, think.

As verbs, cogitate is a hyponym of ruminate; that is, cogitate is a word with a more specific, narrower meaning than ruminate:

ruminate: reflect deeply on a subject
cogitate: consider carefully and deeply; reflect upon; turn over in one's mind

Other hyponyms of ruminate include premeditate, theologise, theologize, introspect, bethink, question, wonder, puzzle, consider, study.

ruminate (verb)	cogitate (verb)
reflect deeply on a subject	use or exercise the mind or one's power of reason in order to make inferences, decisions, or arrive at a solution or judgments
chew the cuds	consider carefully and deeply; reflect upon; turn over in one's mind