Words/Phrases in other languages that don't have an English equivalent.

[Dave Gray]

The American product Segway, for example.  It's probably called a Segway in France, too.  But that's an item, like a croissant or taco.  I think Deju Vu fits, except it's become so common, that the English language has basically absorbed it.

[fyo]

Segway is a brand name. Doesn't share much with croissant or taco, IMHO.

[Brian Fein]

Segway is a brand name. Doesn't share much with croissant or taco, IMHO.

Agree with this.  Its a proper name of a product.  Like iPhone.  Even though there is a spanish word for "phone," its not called a iTelefono in Spain.

[MyGodWearsAHoodie]

Croissant would fall to Dave's "just a thing" rule .

There are a lot of these "specific things" words, e.g. fleur-de-lis.

Or as my 3rd grade teacher like to call them...nouns.  There is a difference schadenfreude which is an entire concept and simply using the local word to describe a type of food like taco or a boat type like canoe. 

[Dave Gray]

Nouns can be ideas, too.  Which is why I didn't use that word. 

In the case of Segway, yes it's a brand, but I think it's one of those brands that becomes a noun, like Band-Aid or Kleenex.  By the way, did you know that band-aid changed its song to "stuck on band aid BRAND, 'cause band aid's stuck on me", so that they didn't lose the rights to the copyright?

[fyo]

Or as my 3rd grade teacher like to call them...nouns.  There is a difference schadenfreude which is an entire concept and simply using the local word to describe a type of food like taco or a boat type like canoe. 

Schadenfreude is a noun...