Definition of: monarch

(mon′ərk) noun
1. A sovereign, as a king or emperor; in modern times, usually, a hereditary constitutional sovereign; originally, the sole ruler of a nation.
2. One who or that which surpasses others of the same kind.
3. A large, orange-brown butterfly (Danaus menippe) whose larva feeds on milkweed: also called milkweed butterfly. See synonyms under MASTER. [<LL monarcha <Gk. monarchēs <monarchos ruling alone <monos alone + archein rule]
—mo·nar·chal (mə·när′kəl) adjective
—mo·nar′chal·ly adverb