noun

• The male monarch or ruler of an empire.
• Any monarch ruling an empire, irrespective of gender, with "empress" contrasting to mean the consort of an emperor.
• (political theory) Specifically, the ruler of the Holy Roman Empire; the world-monarch.
• (tarot) The fourth trump or major arcana card of the tarot deck.
• A large, relatively valuable marble in children's games.
• Any fish of the family Lethrinidae.
• (entomology) Any of various butterflies of the subfamily Charaxinae.
• (entomology) Any of various large dragonflies of the cosmopolitan genus Anax.
• An emperor penguin.
• The title of an emperor.
• Alternative form of emperor (emperor penguin). [The male monarch or ruler of an empire.]