mull vs cogitate

mull is a noun but cogitate is not a noun.

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

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

mull: 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 mull include cerebrate, think.

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

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

mull (noun)	cogitate (noun)
a term used in Scottish names of promontories

mull (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
heat with sugar and spices to make a hot drink	consider carefully and deeply; reflect upon; turn over in one's mind