We have a target value for $ x $ called $ x_t $, and we have the average value for $ x $ given as $ \overline x $. If we take the absolute value of the average minus the target we get a measure of how far on average we were from the target. What is this measurement called?
Expressed as a formula:
$ y = \left| \overline x - x_t \right| $
This is known as an absolute deviation. They appear in different areas in statistics, most notably being the sample variance $s^2$ and sample standard deviation $s$