This article relies largely or entirely on a single source. (October 2016)
It is short for the obsolete word "hockamore", which is an alteration of "Hochheimer", derived from the name of the town of Hochheim am Main in Germany.
The term seems to have been in use in the 17th century, initially for white wines (predominantly Riesling) from the Rheingau, but in the 18th century it came to be used for any German white wine sold in Britain to convey some of the then very high prestige of Rheingau wine to (often much) lesser German wines.
It seems probable that Queen Victoria's visit to Hochheim (in Rheingau) and its vineyards during harvest time in 1850 contributed to the continued use of the word "hock". By then these Rheingau wines commanded high prices, on par with - and sometimes higher than - the best wines from Bordeaux and Burgundy, matching and sometimes exceeding them in prestige.
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Today "hock" is occasionally seen on bottles of (mostly cheaper) white wine sold in the United Kingdom. In Australia, hock is still known as the main ingredient of an old-fashioned summer drink called "hock, lime, and lemon".
The Waterbridge candy company in England makes wine gums. One of the candies is stamped with the flavour Hock.