Definition of border state
1
sometimes capitalized B&S
a
: a state (such as Delaware, Maryland, Virginia, Kentucky, or Missouri) bordering on an antislavery state and favoring slavery before the Civil War
b
: a state (such as Maryland, West Virginia, Kentucky, Missouri, Oklahoma, or Tennessee) just north of the Solid South and traditionally voting Democratic
c
: a state (such as Montana or North Dakota) bordering on Canada
2
: a small country (such as Poland) bordering on a larger more powerful country;
especially
: such a country lying between two larger more powerful countries : buffer state
