old man vs man

old man and man both are nouns.

Word	Noun	Adjective	Verb	Adverb
old man	Yes	No	No	No
man	Yes	No	Yes	No

As nouns, man is a hypernym of old man; that is, man is a word with a broader meaning than old man:

Other hypernyms of old man include adult male, golden ager, old person, oldster, senior citizen.

As nouns, man is a hypernym of old man; that is, man is a word with a broader meaning than old man:

Other hypernyms of old man include adult male.

old man (noun)	man (noun)
an informal term for your father	all of the living human inhabitants of the earth
a man who is very old	any living or extinct member of the family Hominidae characterized by superior intelligence, articulate speech, and erect carriage
a familiar term of address for a man	game equipment consisting of an object used in playing certain board games
(slang) boss	an adult person who is male (as opposed to a woman)
aromatic herb of temperate Eurasia and North Africa having a bitter taste used in making the liqueur absinthe	someone who serves in the armed forces; a member of a military force
	the generic use of the word to refer to any human being
	a manservant who acts as a personal attendant to his employer
	an adult male person who has a manly character (virile and courageous competent)
	a male person who plays a significant role (husband or lover or boyfriend) in the life of a particular woman
	a male subordinate

old man (verb)	man (verb)
	provide with workers
	take charge of a certain job; occupy a certain work place