Altimeter setting is the value to which the barometric pressure scale of the altimeter is set so the altimeter indicates

Explanation

The altimeter setting is the local pressure corrected to sea level so that, set in the Kollsman window, the altimeter reads the field elevation, which is true altitude (height above mean sea level), on the ground at the station. Absolute altitude on the ground would be zero, and 'calibrated altitude' is not what the setting provides.