A cocktail made by combining liquor with lemon juice and a little sugar. It's usually shaken with crushed ice and can be strained and served On the Rocks or Straight Up. Sours are often garnished with an orange slice and a Maraschino Cherry. Though the whiskey sour is probably the most famous of these cocktails, they can be made with many other liquors including bourbon, gin and rum. Sour adj. Having a sharp, tart taste, usually from an acidic ingredient such as lemon juice or vinegar.