Yes, empire is a Scrabble word!

Noun

1. The domain ruled by an emperor or empress; the region over which imperial dominion is exercised

2. A group of countries under a single authority

3. A monarchy with an emperor as head of state

4. A group of diverse companies under common ownership and run as a single organization

5. An eating apple that somewhat resembles a McIntosh; used as both an eating and a cooking apple