light second

English Thesaurus

1. the distance light travels in a vacuum in one second; approximately 300,000 kilometers (noun.quantity)

hypernym	:	astronomy unit,
definition	:	a linear unit used for astronomical distances (noun.quantity)

part meronym	:	light year, light-year,
definition	:	the distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometers (noun.quantity)