From wiki: """[edit] The term "Zahlring" (number ring) was coined by David Hilbert in 1892 and published in 1897.[9] In 19th century German, the word "Ring" could mean "association", which is still used today in English in a limited sense (e.g., spy ring),[10] so if that were the etymology then it would be similar to the way "group" entered mathematics by being a non-technical word for "collection of related things". According to Harvey Cohn, Hilbert used the term for a ring that had the property of "circling directly back" to an element of itself.[11"""