IN THE DICTIONARY
'(<a href="http://www.j-archive.com/media/2006-04-06_DJ_28.jpg" target="_blank">Jon of the Clue Crew measures what looks to be a small pipe or shell in the <i>Jeopardy!</i> science lab.</a>)  These 2 words, 1 derived from the other, refer to the instrument I'm using & the <a href="http://www.j-archive.com/media/2006-04-06_DJ_28a.jpg" target="_blank">measurement</a> I'm taking'
calipers & caliber (calipers & calibration accepted)