The Pacific Northwest, abbreviated PNW, or PacNW is a region in the northwest of North America (the term refers to the land, not the ocean). There are several partially overlapping definitions but the term Pacific Northwest should not be confused with the Northwest Territory (aka the Great Northwest) or the Northwest Territories. The term Northwest Coast is often used when referring only to the coastal regions. The term Northwest Plateau has been used to describe the inland regions, although they are commonly referred to as "the Interior" (which in British Columbia is by convention capitalized and is used as a proper name). The inland portion of the U.S. is called the Inland Empire.

The region's biggest cities are Vancouver, British Columbia ; Seattle, Washington ; and Portland, Oregon .

The area's biomes and ecoregions are distinct from the surrounding areas. The Georgia Strait-Puget Sound basin is shared between British Columbia and Washington, and the Pacific temperate rain forests, comprising the world's largest temperate rain forest zone, stretch along the coast from Alaska to California. The dryland area inland from the Cascade Range and Coast Mountains is very different from the terrain and climate of the Coast, and comprises the Columbia and Fraser Plateaus and mountain ranges contained within them. The interior regions' climates are a northward extension of the Great Western Desert which spans the Great Basin farther south, although by their northern reaches dryland and desert areas verge with boreal forest and various alpine flora regimes.