Niger nī´jər, nēzhâr´ [key], officially Republic of Niger, republic (2005 est. pop. 11,666,000), 489,189 sq mi (1,267,000 sq km), W Africa. It borders on Burkina Faso and Mali in the west, on Algeria and Libya in the north, on Chad in the east, and on Nigeria and Benin in the south. Niamey is