Nigeria (nījir'ēu) [key], officially Federal Republic of Nigeria, republic (2006 provisional pop. 140,003,542), 356,667 sq mi (923,768 sq km), W Africa. It borders on the Gulf of Guinea (an arm of the Atlantic Ocean) in the south, on Benin in the west, on Niger in the northwest and north, on Chad in the northeast, and on Cameroon in the east. Abuja is the capital and Lagos is the largest city.
