Entry 2 senses Webster, 1913 Imperatorial /(ĭm*pĕr`ȧ*tō"rĭ*val)/ · Im·per·a·to·ri·al · IPA 01 a. Commanding; imperative; authoritative. 1. Commanding; imperative; authoritative. 2. Of or pertaining to the title or office of imperator.