'Keystone State' definitions:
Definition of 'Keystone State'
(from WordNet)
noun
A Mid-Atlantic state; one of the original 13 colonies [syn: Pennsylvania, Keystone State, PA]
Definition of 'Keystone State'
From: GCIDE
- Keystone State \Key"stone` State\ Pennsylvania; -- a nickname alluding to its having been the central one of the 13 original United States, at the time of formation of the Constitution. [Webster 1913 Suppl.]