If you want to be precise, it is called a 'matrix'
A matrix is a negative of the actual die. The actual die would have been forged/engraved to look like the finished token. Negative dies have to be made to use for the actual striking process.
Usually, the original die would be hardened and used to strike a number of negatives, so that a mint could run more than one press at once.

The equivalent in the chip manufacturing process are called 'cups'. Obviously they have to be made in pairs.
When we see "errors" like Paul-Son chips with short cane one side/long side the other, it is because the operator failed to load a 'pair' into a mold, rather a single each from two different pairs was used.