/ Dictionary / Index F fiat lux*: Meaning and Definition of Find definitions for: fi•at lux Pronunciation: (fē'ät looks' Eng. fē'ät luks', fī'&schwat), [key] — Latin. Latin. let there be light. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. fiat justitia, ruat caelum* fiat money Related Content Daily Word Quiz: diligent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language