a nation's ruler or head of state usually by hereditary right
"The new monarch was crowned after generations of royal families ruled through hereditary succession."
large migratory American butterfly having deep orange wings with black and white markings; the larvae feed on milkweed
"The monarch butterfly migrated south, its vibrant orange wings marked with black veins as it flew past fields where its caterpillars had once feasted on milkweed."
The ruler of an absolute monarchy or the head of state of a constitutional monarchy.
"The visiting monarch signed the treaty in front of cheering crowds before departing the capital."
In plain English: A monarch is a king, queen, emperor, or empress who rules over a country as its head of state for life.
"The monarch visited his kingdom yesterday to meet with local leaders."
Usage: Use "monarch" to refer specifically to a king, queen, emperor, or empress; avoid using it generically for any type of leader unless emphasizing their royal status. Do not confuse this term with "sovereign," which can apply to non-royal heads of state in certain contexts.
The word monarch comes from the Ancient Greek monárkhēs, meaning "sole ruler." It is formed by combining words for "only" and "leader."