Thou (unit)

The thou (abbreviation th) or mil (mainly United States) is a unit of length in the Imperial System and the United States Customary Units. It is equal to  of an inch. This is not to be confused with the old form of "you".

 Etymology 
Thou comes from the Germanic languages, a shortening of thousandth.

Mil comes from the Romance languages, a shortening of mille.

 History 
The thou was introduced in 1844 by Joseph Whitworth as a substitute to traditional fractions such as     which cannot be defined simply in hundredths unlike  (0.25) or  (0.5). Traditional fractions continued to be used, as they were a substantial part of other units of length.

 Length 

 International  Thou  Inch  Millimetre Thou  1    0.0254

 Usage 

The thou is used in engineering and manufacturing mostly.

Category:Units of length
Category:Imperial units