(1):

(n.) A patron deity or presiding genius.

(2):

(n.) A sole or supreme ruler; a sovereign; the highest ruler; an emperor, king, queen, prince, or chief.

(3):

(n.) One superior to all others of the same kind; as, an oak is called the monarch of the forest.

(4):

(n.) A very large red and black butterfly (Danais Plexippus); - called also milkweed butterfly.

(5):

(a.) Superior to others; preeminent; supreme; ruling.