im·pe·ra·tor 
(ĭm′pə-rätôr′, -tər)
(ĭm′pə-rätôr′, -tər)n.
1. An army commander in the Roman Republic.
2. The supreme power of the Roman emperor.
3. The head of state and supreme commander in the Roman Empire, in whose name all victories were won.
[Latin imperātōr; see EMPEROR.]
im·per′a·tori·al (ĭm-pĕr′ə-tôrē-əl) adj.