Noah Webster
Countermark
COUNTERMARK, noun [counter and mark.]
1. A second or third mark put on a bale of goods belonging to several merchants, that it may not be opened, but in the presence of all the owners.
2. The mark of the goldsmiths company, to show the metal to be standard, added to that of the artificer.
3. An artificial cavity made in the teeth of horses, that have outgrown their natural mark, to disguise their age.
4. A mark added to a medal, a long time after it has been struck, by which its several changes of value may be known.
COUNTERMARK, verb transitive To mark the corner teeth of a horse by an artificial cavity, to disguise his age.