from
The Collaborative International Dictionary of English v.0.48
Grog \Grog\ (gr[o^]g), n. [So named from "Old Grog" a nickname
given to Admiral Vernon, in allusion to his wearing a grogram
cloak in foul weather. He is said to have been the first to
dilute the rum of the sailors (about 1745).]
A mixture of spirit and water not sweetened; hence, any
intoxicating liquor.
[1913 Webster]
{Grog blossom}, a redness on the nose or face of persons who
drink ardent spirits to excess. [Collog.]
[1913 Webster]