Source : Webster's Revised Unabridged Dictionary (1913)

Calibrate \Cal"i*brate\, v. i.
   To ascertain the caliber of, as of a thermometer tube; also,
   more generally, to determine or rectify the graduation of, as
   of the various standards or graduated instruments.

Source : WordNet®

calibrate
     v 1: make fine adjustments or divide into marked intervals for
          optimal measuring; "calibrate an instrument"; "graduate
          a cylinder" [syn: {graduate}, {fine-tune}]
     2: mark (the scale of a measuring instrument) so that it can be
        read in the desired units; "he calibrated the thermometer
        for the Celsius scale"
     3: measure the caliber of; "calibrate a gun"