piteous vs poor

piteous is not a noun while poor is a noun.

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

As adjectives, piteous and poor are synonyms defined as:

Other synonyms of piteous include hapless, miserable, misfortunate, pathetic, pitiable, pitiful, wretched.

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

piteous (adjective)	poor (adjective)
deserving or inciting pity	having little money or few possessions
	lacking in quality or substances
	characterized by or indicating poverty
	of insufficient quantity to meet a need
	deserving or inciting pity