Language Of Confusion: Flats, Part I

Another multi-parter. This one should be all new words. I think. Maybe.
 
As the title suggests, we’re looking at the word flat, and the many, many words it’s related to. Some will make sense! Most won’t though. Flat itself showed up in the fourteenth century meaning stretched out—flat as in an apartment didn’t show up until 1801, from the Scottish flat, a story of a house. But that is related to the other flat, just in a kind of roundabout way. Stretched flat is from the Old Norse flatr, from the Proto Germanic flata-, from the Proto Indo European plat-, to spread. The other flat is from the Old English flett, a house or dwelling, which is from the Proto Germanic flatja-, also from plat-. So they started from the same word, diverged through different languages, then became the same word all over again.
 
Plat- is the ancestor of just so many words, flatter included. Well, probably. It showed up in the thirteenth century as flateren/flaterien, from the Old French flater, which could mean to deceive, or to caress, or to throw to the ground, and that’s thought to be from the Proto Germanic flata-. There are some theories as to how flat could have morphed into meaning flatter, like the caress thing being associated with a flat hand or to throw yourself onto the flat of the ground. Wouldn’t it be funny if flatter isn’t related at all? I mean, it’s happened before!
 
Next, flounder. Um, like the fish, not to flounder, which might not be related to the fish at all. As the noun, flounder showed up in the fourteenth century from the Anglo French floundre, from the Old North French flondre, from the Old Norse flydhra. That’s traced to the Proto Germanic flunthrjo, which is a “nasalized” version of plat-. Basically, they started saying plat- funny and named the fish after that.
 
Now we’ll look at flan, the food, really, I told you it would get weird. Flan showed up in 1846, relatively late, from the French flan, which is thought to be derived from the Frankish flado. It’s descended from the Proto Germanic flathon, flat cake, and that just has to be from plat-. So flan is a flat cake, but they dropped the T and added an N.
 
Next week: more weirdness!
 
Sources
Online Etymology Dictionary
Omniglot
University of Texas at Austin Linguistic Research Center
University of Texas at San Antonio’s page on Proto Indo European language
Tony Jebson’s page on the Origins of Old English
Old English-English Dictionary
Encyclopaedia Britannica
Fordham University