mon·arch 
(mŏnərk, -ärk′)
(mŏnərk, -ärk′)n.
1. One who reigns over a state or territory, usually for life and by hereditary right, especially:
a. A sole and absolute ruler.
b. A sovereign, such as a king or empress, often with constitutionally limited authority: a constitutional monarch.
2. One that commands or rules: "I am monarch of all I survey" (William Cowper).
3. One that surpasses others in power or preeminence: "Mont Blanc is the monarch of the mountains" (Byron).
4. A monarch butterfly.
[Middle English monarke, from Old French monarque, from Late Latin monarcha, from Greek monarkhos : mono-, mono- + arkhein, to rule.]
mo·narchal (mə-närkəl), mo·narchic (-kĭk), mo·narchi·cal (-kĭ-kəl) adj.
mo·narchal·ly, mo·narchi·cal·ly adv.