Definitions clarify central excise terms and who qualifies as an assessee, shaping assessment and duty obligations. Definitions set the scope for the Central Excise Rules, 2017: Act means the Central Excise Act, 1944; assessment includes self-assessment and provisional assessment; assessee covers persons liable for duty, producers/manufacturers, registered private-warehouse persons and their authorised agents; Board denotes the Central Board of Excise and Customs; duty refers to duty payable under the Act; notification means publication in the Official Gazette; and warehouse means premises registered under the rules; undefined terms take meanings from the Act.