The Low Countries
This refers to a group of three lowland countries in Western Europe: Belgium, the Netherlands, and Luxembourg. Large amounts of land in these countries is below sea level, hence the name. The three countries are politically aligned via a 1960 treaty.
In many contexts, these three countries are often referred in aggregate as “Benelux.”
I talked to a Dutch friend about it. She said she had never heard of the English phrase “the low countries,” but then said:
De lage landen I know. But I always thought that was just NL.
“De lage landen” is Dutch for – wait for it – “the low countries.” She said she knew it as a reference to the region, but had never thought about what it meant in literal terms. She noted that “De Lage Landen” is a major financial services company in her country.
I talked to another Dutch friend, and got the same response: he didn’t know what “the low countries” meant, but immediately knew “de lage landen” (strange, since both friends were fluent in English, and would have had to have known the translation).
He also made the point that “neder” from “Nederlands” (the Dutch spelling of “Netherlands”) literally means “low”:
If I would translate it to English, something like: “low” or “below.” It’s the same prefix used in the Dutch word for “humble.”
So the name of The Netherlands is literally something like “the low lands.”
Notably, neither friend had any concept that “De lage landen” referred to anything beyond The Netherlands.
Why I Looked It Up
I had heard the term for years, but it came up multiple times in a book about the history of World War 1. Germany invaded France through The Low Countries, specifically Belgium.