Denatured spirits. Industrial spirits denatured in accordance with approved formulas in distilled spirits plants established and operated under the provisions of this chapter relating to the establishment and operation of plants qualified to denature spirits in the United States or, in respect of a product of the Virgin Islands, shall also mean spirits denatured in accordance with approved formulas in plants established under the provisions of the Virgin Islands regulations and shall include, unless otherwise limited, both completely and specially denatured spirits.
27 CFR § 26.11
When used in this part and in forms prescribed under this part, where not otherwise distinctly expressed or manifestly incompatible with the intent thereof, terms shall have the meaning ascribed in this section. Words in the plural form shall include the singular and vice versa, and words importing the masculine gender shall include the feminine. The terms includes and including do not exclude things not enumerated which are in the same general class.