the chief city of Pennsylvania, on the Delaware River; population 1,447,395 (est. 2008). Established as a Quaker colony by William Penn and others in 1681, it was the site in 1776 of the signing of the Declaration of Independence and in 1787 of the adoption of the Constitution of the United States.
noun & adjective
from Greek philadelphia 'brotherly love'
Philadelphia in other Oxford dictionaries
Definition of Philadelphia in the US English dictionary