western hemisphere

Short definition from Wiktionary

Noun

1. 1
   Alternative form of Western Hemisphere.
2. 2
   Used other than figuratively or idiomatically: see western, hemisphere.

Proper noun

1. 1
   The hemisphere in Earth to the west of the Greenwich meridian (zero degree longitude) and east of 180 degrees longitude (approximately the International Date Line), containing the Americas and a small part of eastern Russia.
2. 2
   The Americas.