Pronunciation: (gē-an'u, -ä'nu, gī-an'u),[key] —n. 1. a vast tropical region in NE South America, bounded by the Orinoco, Negro, and Amazon rivers and the Atlantic. ab. 690,000 sq. mi. (1,787,000 sq. km).
2. the coastal portion of this region, which includes Guyana, French Guiana, and Suriname. 1,263,200; 175,275 sq. mi. (453,962 sq. km).