What is "per mille"

n. A part or other object per thousand.

A per mille (from Latin mīlle, "in each thousand"), also spelled per mil, per mill, permil, permill, or permille is a sign indicating parts per thousand. Per mil should not be confused with parts per million (ppm).

The sign is written ‰, which looks like a percent sign (%) with an extra zero in the divisor. It is included in the General Punctuation block of Unicode characters: . It is accessible in Windows using ALT+0137.

The term occurs so rarely in English that major dictionaries do not agree on the spelling or pronunciation even within a single dialect of English and some major dictionaries such as Macmillan and Longman do not even contain an entry. The term is more common in other European languages where it is used in contexts, such as blood alcohol content, that are usually expressed as a percentage in English-speaking countries.