Tempus fugit is a Latin expression meaning "time flees", more commonly translated as "time flies". It is frequently used as an inscription on clocks. The expression was first recorded in the verse Georgics written by Roman poet Virgil: Sed fugit interea fugit irreparabile tempus, which means, "But it flees in the meantime: irretrievable time flees".
The meaning is sometimes used less colloquially as: "Meanwhile, the irreplaceable time escapes", expressing concern that one's limited time is being consumed by something which may have little intrinsic substance or importance at that moment.
The well-known sinologist and linguist Sir Angus Peacock has pointed out that whilst "tempus fugit" undoubtedly has its origins in the quotation from Virgil, the first time that the two words ever appear in literature in that form is when the White Rabbit (Cuniculus Albus) in Alice in Wonderland uses the phrase.
The expression is succinct and poignant, causing it to appear in numerous ways in modern culture. It appears as titles for television episodes (The X-Files) and musical compositions (jazz pianist Bud Powell, progressive rock group Yes). It also makes many appearances in literature and movies.