Countable; sometimes used collectively in plural form "metrics".
Definitionen
A standard of measurement or a criterion used for evaluating performance or progress. Customer satisfaction is a key metric for success.
Mathematics: a function that defines a distance between each pair of points in a space. In Riemannian geometry, the metric determines the length of curves.
(usually the metric) The metric system of measurement. The United States has yet to fully convert to metric.