nines
n.— «The copper was OFHC grade; the zinc was five nines pure.» —“United States. National Bureau of Standards” Preparation of NBS White Cast Iron Spectrochemical Standards , 1918. (source: Double-Tongued Dictionary)
Further reading
You may have a favorite word in English, but what about your favorite in another language? The Spanish term ojalá is especially handy for expressing hopefulness and derives from Arabic for “God willing.” In Trinidad, if you want to ask...
If someone urges you to spill the tea, they probably don’t want you tipping over a hot beverage. Originally, the tea here was the letter T, as in “truth.” To spill the T means to “pass along truthful information.” Plus...