What unit of time is equal to one thousandth of a second?

Millisecond is a time measurement unit with the symbol of ms, which is equal to a one thousandth of a second. It can also be defined as the duration of photo flash light, or as the time of a cycle for 1kHz frequency. This unit is sometimes used when measuring magnitude or making really precise physical and scientific calculations.

Second is a standard time measurement unit recognized and used by the International System of Units. Second is equal to 1/60th of a minute or 1/3,600 of an hour. This is one of the oldest time measurement units used by early Egyptian, Persian, Hellenistic, and other civilizations. The name is derived from Latin expression meaning 'the second division of hours'. Second is also a basic reference unit for some really precise time measurement units like millisecond, microsecond, nanosecond, etc.

A unit of 10 milliseconds may be called a centisecond, and one of 100 milliseconds a decisecond, but these names are rarely used. A decisecond equals 1/10th of a second and a centisecond equals 1/100th of a second.