poor vs piteous

poor is a noun but piteous is not a noun.

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

As adjectives, poor and piteous are synonyms defined as:

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

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

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