t'sun

   1. a Chinese unit of distance equal to 0.1 ch'ih or about 1.41 inches (3.58 centimeters).

   2. a unit of relative distance used in acupuncture. One t'sun is the distance between the two outer folds in the bent middle finger, or (according to some sources) the width of the thumb. This is a personal unit, different for each person and used to locate acupuncture points on that person's body. The unit is also spelled cun and is sometimes called the anatomical Chinese inch (ACI) or body inch in English.