Today I Learned…

…why you can’t have any other kinds of nog besides egg.

When cartons are printed “Egg Nog,” it’s a bit of a misnomer.  More accurately, the popular holiday beverage should be known as “Eggnog”– one word.  From Wikipedia:

The origins, etymology, and even the ingredients used to make the original eggnog drink are debated. Eggnog, or a very similar drink, may have originated in East Anglia, England, though it may also have been developed from posset (a medieval European beverage made with hot milk). An article by Nanna Rögnvaldsdóttir, an Icelandic food expert, states that the drink adopted the nog part of its name from the word noggin, a Middle English phrase used to describe a small, wooden, carved mug used to serve alcohol. Another name for this British drink was Egg Flip. Yet another story is that the term derived from the name egg-and-grog, a common Colonial term used to describe rum. Eventually the term was shortened to egg’n’grog, then eggnog.

Therefore, there is no such class of beverage as the “nog.”  Something like soy nog — which is exactly what it sounds like — is in fact a bit of a retronym.