The territory sold by France to the US in 1803, comprising the western part of the Mississippi valley and including the modern state of Louisiana.
Definition of Louisiana Purchase in US English:
Louisiana Purchase
proper noun
The territory sold by France to the US in 1803, comprising the western part of the Mississippi valley and including the modern state of Louisiana. The area had been explored by France, ceded to Spain in 1762, and returned to France in 1800.