Per Mille is part per thousand. So, 1 mille is 1/1000 fraction. This term is commonly used in European countries, and it is used to represent fractions smaller than 1%.
The corresponding symbol is ‰. It resembles percent sign but per mille symbol has an extra 0 in the divisor.
The other accepted spellings are: permille, permil, permill, per mille, per mil, per mill.
In Latin Per Mille refers to “in each thousand”.