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 (Aptenodytes forsteri).