imperator
Concise Oxford English Dictionary © 2008 Oxford University Press:
imperator /ˌɪmpəˈrɑːtɔː/
▶noun Roman History commander (a title conferred under the Republic on a victorious general and under the Empire on the emperor).
– derivatives
imperatorial /ˌɪmpɛrəˈtɔːrɪəl, ɪmˌpɛrə-/ adjective.
imperatorial /ˌɪmpɛrəˈtɔːrɪəl, ɪmˌpɛrə-/ adjective.
– origin L., from imperare ‘to command’.
'imperator' also found in these Oxford entries:

