1911 Encyclopædia Britannica/Caliver

CALIVER, a firearm used in the 16th century. The word is an English corruption of “calibre,” and arises from the “arquebus of calibre,” that is, of standard bore, which replaced the older arquebus. “Caliver,” therefore, is practically synonymous with “arquebus.” The heavier musket, fired from a rest, replaced the caliver or arquebus towards the close of the century.