grog, originally a mixture of rum and water. It is named after Admiral Grogram Vernon, who first ordered the dilution of the British Royal Navy's daily rum ration. The term is now applied to almost any unsweetened mixture of spirits and water, hot or cold, and it is sometimes used for any intoxicating drink: hence, groggy.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.