Wine. Still wine, vermouth, or other aperitif wine, imitation, substandard, or artificial wine, compounds designated as wine, flavored, rectified, or sweetened wine, champagne or sparkling wine, and artificially carbonated wine, containing not over 24 percent of alcohol by volume. Wines containing more than 24 percent of alcohol by volume are classed and taxed as distilled 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.