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.
Give them 25.4 millimetres and they'll take 1.6093 kilometres!
by Hodgit August 06, 2004
The length of the path travelled by light in a vacuum during the time interval of 1/299792458 seconds.
The caesium 133 atom can switch periods of radiation 30.663318988498369762190615215544 times in the time it takes light to travel 1 metre.
by lj90 September 14, 2007