doctor vs John Langdon Down

doctor and John Langdon Down both are nouns.

Word	Noun	Adjective	Verb	Adverb
doctor	Yes	No	Yes	No
John Langdon Down	Yes	No	No	No

doctor (noun)	John Langdon Down (noun)
children take the roles of physician or patient or nurse and pretend they are at the physician's office	English physician who first described Down's syndrome (1828-1896)
a licensed medical practitioner
a person who holds Ph.D. degree (or the equivalent) from an academic institution

doctor (verb)	John Langdon Down (verb)
give medical treatment to
alter and make impure, as with the intention to deceive
restore by replacing a part or putting together what is torn or broken