Look up nanosecond in Wiktionary, the free dictionary.
A nanosecond (ns) is a unit of
time in the
International System of Units (SI) equal to one billionth of a
second, that is, 1⁄1 000 000 000 of a second, or 10−9 seconds.
The term combines the
SI prefixnano- indicating a 1 billionth submultiple of an SI unit (e.g. nanogram,
nanometre, etc.) and second, the primary unit of time in the SI.
A nanosecond is equal to 1000
picoseconds or 1⁄1000microsecond. Time units ranging between 10−8 and 10−7 seconds are typically expressed as tens or hundreds of nanoseconds.
^By definition of the "foot" as exactly 1/3 yards, and of the
international yard as "exactly 0.9144 metres", and of the metre (SI unit) defined by the
International Bureau of Weights and Measures as the "length of the path traveled by light in vacuum during a time interval of 1/299792458 of a second". The time taken by light to travel 1 foot in a vacuum is therefore (1/299792458)x(0.9144/3) seconds, or 1.016703362164 nanoseconds.