city vs Pittsburgh

city and Pittsburgh both are nouns.

Word	Noun	Adjective	Verb	Adverb
city	Yes	No	No	No
Pittsburgh	Yes	No	No	No

city (noun)	Pittsburgh (noun)
people living in a large densely populated municipality	a city in southwestern Pennsylvania where the confluence of the Allegheny River and Monongahela River forms the Ohio River; long an important urban industrial area; site of Carnegie Mellon University and the University of Pittsburgh
a large and densely populated urban area; may include several independent administrative districts
an incorporated administrative district established by state charter