Metre

[Kai]

[The length] of [the path] travelled by light in a [vacuum] during the time interval of 1/299792458 seconds.

[Sommer]

A measure of length, the base unit for length in the [metric] scale. Although spelt [meter] in the United States, the [proper spelling] is metre.

[Agnes]

n. [impractical] French unit of length based roughly on the circumference of the earth. Supporters claim that metres (and other [metric] measures) are more practical than Imperial measures despite [the invention] of the metric foot (0.3 metres) and the metric yard (0.9 metres), which defy the point of metrication.