mid-15c., from Middle French monarque (14c.) or directly from Late Latin monarcha, from Greek monarkhes "one who rules alone" (see monarchy). As a type of large butterfly, from 1890.
any of about 60 bird species constituting the subfamily Monarchinae of the Old World flycatcher family Muscicapidae. The term monarch is usually reserved for members of the Australian and Asian genera Monarcha and Hypothymis; the members of about 12 other Asian and African genera of monarchines are called flycatchers, with various modifiers.