A unit of time or time unit is any particular time interval, used as a standard way of measuring or expressing duration, the exact modern definition, is from the National Institute of Standards and Technology (NIST), a measurement standards laboratory, and a non-regulatory agency of which organization?
Unit of time A unit of time or time unit is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI), and by extension most of the Western world, is the second, defined as about 9 billion oscillations of the caesium atom. The exact modern definition, from the National Institute of Standards and Technology is:
Horometry Horometry is the art, practice or method by which time is measured in hours or by smaller units. By this account, a "horometer" (Greek: hour + -meter ) is an instrument that measures time.