In the Bag

I was getting something out of my knapsack this afternoon when it occurred to me that I have no idea where the word "knapsack" comes from.

I mean, the "sack" part is obvious enough: a sack is a large bag. It's an old word, too: like many simple, basic words that we use all the time, it hasn't changed much in the millennia. It started out life as a Semitic word that made it into Greek as "sakkos", Latin "saccus", and Hebrew "saq", and spread to many of the Indo-European languages (and others besides) more or less unchanged: French "sac", German "Sack", Italian "sacco", Hungarian "zsàc", Dutch "zak", even Finnish "säkki".

But the "knap-" part? Not what you might have expected. It's evidently from Low German "knappen", literally "to snap or crack" and from there metaphorically "to eat", so a knapsack is something in which you keep your meal as you trudge up the Alps.

Germans have another word for the same thing that we occasionally see in English, "rucksack", and this one is more straightforward: "zuruck" is an adjective meaning "[to the] back", "ruck" itself means "back", and so a rucksack is one that you strap to your back rather than carry in your hand.

You may have seen in the liquor store this product: Dry Sack Sherry, sold in a burlap sack.

Clever! And completely wrong etymologically. Nothing to do with sacks at all. "Sec" is the French word for "dry", so a sherry that is dry, as opposed to being sweet, was sec. This in English eventually mutated into "sherry sack", and eventually just "sack". You will probably have heard this term in Shakespeare, as in this quote from Henry IV:

Thou art so fat-witted, with drinking of old sack
and unbuttoning thee after supper and sleeping upon
benches after noon, that thou hast forgotten to
demand that truly which thou wouldst truly know.

"Sherry", by the by, comes from Jerez, previously Xeres, the Spanish town in which such wine was originally made.