Metric time

Metric time is the measure of time interval using the metric system, which defines the second as the base unit of time, and multiple and submultiple units formed with metric prefixes, such as kiloseconds and milliseconds. It does not define the time of day, as this is defined by various time scales, which may be based upon the metric definition of the second. Other units of time, the minute, hour, and day, are accepted for use with the modern metric system, but are not part of it.

History

Although part of the decimal metric system, the second derives its name from the sexagesimal system, which originated with the Sumerians and Babylonians, and divides a base unit into sixty minutes, minutes into sixty seconds, seconds into sixty thirds, etc. The word "minute" comes from the Latin pars minuta prima, meaning first small part, and "second" from pars minuta secunda or second small part. Coincidentally, angular measure also uses these sexagesimal units; in that field, it is the degree that is subdivided into minutes and seconds, while in time, it is the hour.