In bond. When used to describe spirits, denatured spirits, articles, or wine, this term refers to spirits, denatured spirits, articles, or wine held under bond to secure the payment of the taxes imposed by 26 U.S.C. chapter 51, and on which those taxes have not been determined. Spirits, denatured spirits, articles, or wine are considered to be held under bond if they are held by a proprietor who is liable for the tax, even if the proprietor is not required to provide a bond under this chapter. The term also refers to such spirits, denatured spirits, articles, or wine on the bonded premises of a distilled spirits plant, and such spirits, denatured spirits, or wines that are in transit between bonded premises (including, in the case of wine, bonded wine cellar premises). In addition, the term refers to spirits in transit from customs custody to bonded premises, and spirits withdrawn without payment of tax under 26 U.S.C. 5214, and with respect to which relief from liability has not occurred under 26 U.S.C. 5005(2).
27 CFR § 19.1
As used in this part, the following terms shall have the meanings indicated unless either the context in which they are used requires a different meaning, or a different definition is prescribed for a particular subpart, section, or portion of this part: