"John Barleycorn." YourDictionary, n.d. Web. 17 August 2018. <http://www.yourdictionary.com/john-barleycorn>.
John Barleycorn. (n.d.). Retrieved August 17th, 2018, from http://www.yourdictionary.com/john-barleycorn
John (commonly used to personify a concept) + barleycorn; barley is used to produce malt the source of most British alcoholic drink.