a) the northeastern states of the US, especially during the Civil War (1861-65) when they fought against the South. Today, the six states in New England and the states of New York, New Jersey, and Pennsylvania are usually called the Northeast,and the states to the west of these are called the Midwest. People from the northern part of the US are called Northerners.
b) the northern part of England, which includes the area north of the Midlands and south of the Scottish border, and contains several large cities, including Manchester, Leeds, Liverpool, and Newcastle.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.