[(a) adjudicating authority means any authority competent to pass any order or decision under this Act, but does not include the Central Board of Excise and Customs constituted under the Central Boards of Revenue Act, 1963 (54 of 1963) [Commissioner]9 of Central Excise (Appeals) or Appellate Tribunal;

(aa) Appellate Tribunal means the Customs, Excise and 10[Service Tax] Appellate Tribunal constituted under Section 129 of the Customs Act, 1962 (52 of 1962);]