Also, permil, per mil, per mille, promille
1) per (every) thousand (Latin)
2) one thousandth
3) the fraction 1/1000
4) the decimal 0.001
5) the symbol ‰
Baseball batting averages are written as a permille.
Legal limits blood alcohol content for driving a road vehicle in some countries are 0.5‰ or 0.2‰.