calliper
(also caliper), / ˈkælɪpə(r); `kæləpɚ/ n
1 [C usu pl 通常作复数]
metal support for weak or injured legs 双脚规形夹（因腿部无力或损伤而使用的金属支架）.
2 callipers [pl]
instrument for measuring the diameter of tubes or round objects 测径器; 双脚规; 卡钳
a pair of callipers 一把测径器. =>illus 见插图.