old man vs slang

old man and slang both are nouns.

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

old man (noun)	slang (noun)
an informal term for your father	a characteristic language of a particular group (as among thieves)
a man who is very old	informal language consisting of words and expressions that are not considered appropriate for formal occasions; often vituperative or vulgar
a familiar term of address for a man
(slang) boss
aromatic herb of temperate Eurasia and North Africa having a bitter taste used in making the liqueur absinthe