the United States (especially the northern states during the American Civil War)

the region of the United States lying to the north of the Mason-Dixon line

in or characteristic of a region of the United States south of (approximately) the Mason-Dixon line

the United States (especially the northern states during the American Civil War)

the region of the United States lying to the north of the Mason-Dixon line

used to signify the Union forces in the American Civil War (who wore blue uniforms)

being of or having to do with the northern United States and those loyal to the Union during the American Civil War

used by Southerners for an inhabitant of a northern state in the United States (especially a Union soldier)