Here's why:
* Empress refers specifically to the female ruler of an empire.
* Emperor is the corresponding term for the male ruler.
While there isn't a word for a "male empress," here are some options depending on the context:
* Emperor: This is the most straightforward and common term.
* King: If the empire is ruled by a monarchy, "king" could be used if the male ruler holds the title.
* Monarch: This is a general term for any supreme ruler, regardless of gender.
* Sovereign: This term emphasizes the ruler's independence and power.
It's important to remember that language is constantly evolving, and new terms may emerge in the future to reflect changing societal norms and gender identities.