Western Hemisphere: The half that lies west of the prime meridian and east of the 180th meridian. This hemisphere includes North and South America, the eastern Pacific Ocean, the Caribbean Sea, and the majority of the Atlantic Ocean.

Western Hemisphere The western hemisphere is a geographical term for the half of the Earth that is west of the Prime Meridian. Pretend that the earth is cut in half, from the North Pole, through England, to the South Pole. The Western Hemisphere is the half to the west. The other half is called the Eastern Hemisphere.

Western Hemisphere, part of Earth comprising North and South America and the surrounding waters. Longitudes 20° W and 160° E are often considered its boundaries. Some geographers, however, define the Western Hemisphere as being the half of Earth that lies west of the Greenwich meridian (prime

The Western Hemisphere consists of the Americas, excluding some of the Aleutian Islands to the southwest of the Alaskan mainland; the westernmost portion of Europe, both mainland and islands; the westernmost portion of Africa, both mainland and islands; the extreme eastern tip of the Russian mainland and islands (North Asia); numerous territories in Oceania; and a large portion of Antarctica.