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
Book recommendations and the art of apology. Martha and Grant share some good reads, including an opinionated romp through English grammar, a Spanish-language adventure novel, an account of 19th-century dictionary wars, and a gorgeously illustrated...
The emotional appeal of handwriting and the emotional reveal of animal phrases. Should children be taught cursive writing in school, or is their time better spent studying other things? A handwritten note and a typed one may use the very same words...