caliper, calipers, calliper, callipers - an instrument for measuring the distance between two points

metric linear unit - a linear unit of distance in metric terms

micromillimeter, micromillimetre, millimicron, nanometer, nanometre, nm - a metric unit of length equal to one billionth of a meter

millimeter, millimetre, mm - a metric unit of length equal to one thousandth of a meter