Final answer:
A standard is a level of quality or performance that people accept as normal. In mathematics, a standard unit is one that is commonly used to measure physical quantities.
Step-by-step explanation:
A standard is a level of quality or performance that people accept as normal. It can also be a set unit of measurement for a particular purpose. In mathematics, a standard unit is one that is commonly used to measure physical quantities. For example, the customary and metric systems of measurement both include standard units for weight, length, and liquid volume.