monarch

Concise Oxford English Dictionary © 2008 Oxford University Press:
monarch /ˈmɒnək/

▶noun

• 1 a sovereign head of state, especially a king, queen, or emperor.

• 2 a large migratory orange and black butterfly, chiefly North American, whose caterpillars feed on milkweed. [Danaus plexippus.]

• 3 (also monarch flycatcher) a flycatcher of Africa, Asia, and Australasia, typically with bold plumage. [Family Monarchidae: many species.]

– derivatives
monarchal adjective,
monarchial adjective,
monarchic adjective,
monarchical adjective,
monarchically adverb.

– origin ME: from late L. monarcha, from Gk monarkhēs, from monos ‘alone’ + arkhein ‘to rule’.