A Mason-Dixon line一条梅森
N(名词) the state boundary between Maryland and Pennsylvania: surveyed between 1763 and 1767 by Charles Mason and Jeremiah Dixon; popularly regarded as the dividing line between North and South, esp between the free and the slave states before the American Civil War 梅森-狄克森线(马里兰州和宾夕法尼亚州之间的分界线)