Origin of caliber
Caliber comes from the old French calibre (14c.), from the Arabic qalib "a mold, last", which derives from the Greek calapous [Gr: καλάπους] "a shoemaker's last" lit. "little wooden foot," from calon "wood" + pous "foot".
From the same root: calibrate, calibration.
In modern Greek (Romeika):
a) calapodi: a shoemaker's last, a little wooden foot [Gr: καλαπόδι]
b) calibraro: calibrate [Gr:καλιμπράρω], loanword
See also: http://www.etymonline.com/index.php?search=caliber&searchmode=none