 METRIC

A metric on a set $X$ is a function $d:X\times X\to [0,\infty )$ that is symmetric, satisfies the triangle inequality, and obeys $d(x,y)=0$ exactly when $x=y$.

"METRIC" can refer to different concepts depending on the context. Here are some of the most common interpretations: 1. **Measurement System**: In the context of measurement, METRIC typically refers to the metric system, a decimal-based system of measurement that is used internationally. It includes units such as meters for length, kilograms for mass, and liters for volume.