nine n. in a percentage between 99 and 100, a place on either side of the decimal point given a value of nine and counted in serial to indicate a number very near 100 percent, such as in measurements of reliability, accuracy, purity, etc. Editorial Note: Common forms are five nines, meaning 99.999%, and six nines, meaning 99.9999%. Also used attributively: the company offers five-nines reliability guarantees. (source: Double-Tongued Dictionary)
Further reading
Yvonne from Rock Hill, South Carolina, learned the phrase honor bright as a way of assuring that one was telling the truth, much like cross my heart or I swear to God. It’s common in the UK, and Shakespeare used honour bright in Troilus and Cressida...
David from Plymouth, Wisconsin, wonders about the expression a cord of wood. The phrase goes back to the 17th century and has to do with using a cord to measure a specific quantity of stacked wood. This is part of a complete episode. Transcript of...