# ››Measurement unit: millisecond

Full name: millisecond

Plural form: milliseconds

Symbol: ms

Alternate spelling: millisec

Category type: time

Scale factor: 0.001

# ››SI unit: second

The SI base unit for time is the second.
1 second is equal to 1000 millisecond.

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# ››Definition: Millisecond

The SI prefix "milli" represents a factor of 10-3, or in exponential notation, 1E-3.

So 1 millisecond = 10-3 arcseconds.

The definition of a second is as follows:

A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 (approximately 7.7×10-7) of a circle. It is the angular diameter of an object of 1 unit diameter at a distance of 360×60×60/(2pi) (approximately 206,265 units), such as (approximately) 1 cm at 2.1 km, or, directly from the definition, 1 astronomical unit at 1 parsec.