"tempus fugit." YourDictionary, n.d. Web. 15 May 2018. <http://www.yourdictionary.com/tempus-fugit>.
tempus fugit. (n.d.). Retrieved May 15th, 2018, from http://www.yourdictionary.com/tempus-fugit
Borrowed from Latin, from the verse Georgica which was written by the Roman poet Virgil which is sed fugit interea fugit irreparabile tempus (“but it flees meanwhile: irretrievable time flees") which has the less literal translation "while, the irreplaceable time escapes".
English Wiktionary. Available under CC-BY-SA license.