Factory. The premises of a manufacturer of tobacco products or processed tobacco as described in his permit issued under 26 U.S.C. chapter 52, or the premises of a manufacturer of cigarette papers and tubes on which such business is conducted.
27 CFR § 40.11
When used in this part and in forms prescribed under this part, the following terms shall have the meanings given in this section, unless the context clearly indicates otherwise. Words in the plural form shall include the singular, and vice versa, and words indicating the masculine gender shall include the feminine. The terms includes and including do not exclude things not listed which are in the same general class.