caliber

詳細解釋：

cal.i.ber

n.（名詞）
Abbr. cal.
縮寫 cal.
The diameter of the inside of a round cylinder, such as a tube.
口徑：圓柱體內側圓的直徑，如管道
The diameter of the bore of a firearm, usually shown in hundredths or thousandths of an inch and expressed in writing or print in terms of a decimal fraction:
口徑：火器槍孔的直徑，常以英寸的百分數或千分數表示，在手寫或印刷中常以十進制分數表示：
例句：
.45 caliber.
.45口徑

The diameter of a large projectile, such as an artillery shell, measured in millimeters or in inches.
彈徑：大炮彈的直徑，如炮彈殼，以毫米或英寸計
Degree of worth; quality:
品質，質量；才幹：
例句：
a school of high caliber; an executive of low caliber.
高質量的學校；能力較低的行政官

來源：
French calibre
法文 calibre