brain vs circle of Willis

brain and circle of Willis both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain	Yes	No	Yes	No
circle of Willis	Yes	No	No	No

brain (noun)	circle of Willis (noun)
that part of the central nervous system that includes all the higher nervous centers; enclosed within the skull; continuous with the spinal cord	a ring of arteries at the base of the brain
mental ability
that which is responsible for one's thoughts, feelings, and conscious brain functions; the seat of the faculty of reason
the brain of certain animals used as meat
someone who has exceptional intellectual ability and originality

brain (verb)	circle of Willis (verb)
hit on the head
kill by smashing someone's skull