The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

calibrate
    v 1: make fine adjustments or divide into marked intervals for
         optimal measuring; "calibrate an instrument"; "graduate a
         cylinder" [syn: calibrate, 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"