old man vs patois

old man and patois both are nouns.

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

old man (noun)	patois (noun)
an informal term for your father	a regional dialect of a language (especially French); usually considered substandard
a man who is very old	a characteristic language of a particular group (as among thieves)
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