Tax. Any tax imposed by 26 U.S.C. 5001-5066, or by any corresponding provision of prior internal revenue laws, and in the case of any commodity of a kind subject to a tax under any such sections, any tax equal to any such tax, any additional tax, or any floor stocks tax. The term includes an extraction denominated a tax, and any penalty, addition to tax, additional amount, or interest applicable to any such tax.
27 CFR § 70.501
When used in this subpart, where not otherwise distinctly expressed or manifestly incompatible with the intent thereof, terms shall have the meaning ascribed in this section.