<p><strong>Noun</strong></p><ul><li>Lake Chad, a lake in Africa at the junction of four countries: Cameroon, Chad, Niger, and Nigeria.</li><li>5,000 to 10,000 sq. mi. (13,000 to 26,000 sq. km) (seasonal variation).</li><li>Official name Republic of Chad.</li><li>a republic in northern central Africa, east of Lake Chad.</li><li>501,000 sq. mi. (1,297,590 sq. km).</li></ul>