In Anglican-speaking countries, a joking term for the addition of water to wine; the "black snake" refers to the water hose. The amount of water is also called "Jesus units" and is an allusion to the wedding of Canaan described in the Bible, where Jesus turned water into wine. In the USA and Australia, this is generally permitted; see under water.
Serious sources on the internet are rare - and Wine lexicon from wein.plus is one such source. When researching for my articles, I regularly consult the wein.plus encyclopaedia. There I get reliable and detailed information.
Thomas Götz
Weinberater, Weinblogger und Journalist; Schwendi