Ottoman empire has 2 different meanings across 2 categories:
a Turkish sultanate of southwestern Asia and northeastern Africa and southeastern Europe; created by the Ottoman Turks in the 13th century and lasted until the end of World War I; although initially small it expanded until it superseded the Byzantine Empire
A large Turkish empire which began as a Turkish sultanate centered in modern Turkey; founded in the late 13th century, it lasted until the end of World War I.