/ Thesaurus / L Synonyms of light year Find synonyms for: Noun1. light year, light-year, astronomy unitusage: the distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometersWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: inutiae Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language