poor vs jejune

poor is a noun but jejune is not a noun.

Word	Noun	Adjective	Verb	Adverb
poor	Yes	Yes	No	No
jejune	No	Yes	No	No

As adjectives, poor and jejune are synonyms defined as:

Other synonyms of poor include inadequate, short.

poor (noun)	jejune (noun)
people without possessions or wealth (considered as a group)

poor (adjective)	jejune (adjective)
having little money or few possessions	displaying or suggesting a lack of maturity
lacking in quality or substances	of insufficient quantity to meet a need
characterized by or indicating poverty	lacking interest or significance or impact
of insufficient quantity to meet a need
deserving or inciting pity