ruminative vs brooding

ruminative is not a noun while brooding is a noun.

Word	Noun	Adjective	Verb	Adverb
ruminative	No	Yes	No	No
brooding	Yes	Yes	No	No

As adjectives, ruminative and brooding are synonyms defined as:

Other synonyms of ruminative include broody, contemplative, meditative, musing, pensive, pondering, reflective.

ruminative (noun)	brooding (noun)
	persistent morbid meditation on a problem
	sitting on eggs so as to hatch them by the warmth of the body

ruminative (adjective)	brooding (adjective)
deeply or seriously thoughtful	deeply or seriously thoughtful