The Greek word "monarchia" is the root of the English word "monarchy". The word "monarchia" is derived from the Greek words "monos", meaning "single" or "alone", and "archein", meaning "to rule" or "to have power". Therefore, the word "monarch" refers to a single ruler or a sovereign who has supreme power in a country. The term "monarchy" is used to describe a form of government where the supreme power and authority are vested in a single individual who holds the title of monarch.