Definition of imperial eagle in US English:

imperial eagle

noun

  • Either of two large Eurasian eagles with predominantly dark plumage and pale heads, formerly regarded as conspecific: (more fully Spanish imperial eagle) Aquila adalberti, breeding in Spain, and (more fully eastern imperial eagle) A. heliaca, breeding from south-eastern Europe to central Asia.

Origin

Early 19th century; earliest use found in George Shaw (1751–1813), natural historian. After scientific Latin Falco imperialis, former specific name (1809 or earlier in sense (a), 1821 or earlier in sense (b); compare quots. 1809 and 1821).