Why is the English word "curry" used for all these different dishes? More like meta-cooking question, but I believe it fits here better than on travel stack.

Why is English so poor at differentiating all those different things hidden under one common name: curry?

Is there a historical reason for that, such as similar (for the sailors in XVI century) food from different exotic countries?  Or do they have similar basis, like set of spices, flavors?

Background

There are at least few different dishes (or even dish families) from different countries that western people call curry, even if they are not similar:


India curry, which is I think the general name for multiple versions of thick sauces with meets, including butter chicken, masala chicken, etc.
Thai curries based on more watered-down sauces with notable taste from coconut milk. There are at least 3 of them (red, yellow, green), and in Thai language they are called ngang which is also the general term for soup (I can be wrong on this one).
Japanese curry
Filipino curry
The spice called curry - in stores in Europe you can buy this spice (in packs like black pepper, cumin, oregano, etc.) which is essentially mix of simple spices.
There are probably more things that are translated as curry in English.


So, how to differentiate it all? Do all of those have something in common? Or is it just a lack of distinct wording?
"Curry" is based on the Tamil word "Kari", which refers to any of various highly-spiced side dishes intended to be eaten over rice. Englishmen from the British East India Company encountered the Tamil word in their first explorations of the subcontinent, applied it more broadly to pretty much all Indian dishes, and used it in preference to words in other Indian languages.

By the early 19th century, "Curry houses" were established as restaurants in London.  As a result, when British travellers encountered highly spiced stews in Siam and Japan, they called these "curry" as well.  Many of these dishes were descended from Indian cuisine in any case.

If you're interested in this, I highly recommend getting a copy of Curry: A Tale of Cooks and Conquerors.  It'll give you a history of the last 600 years of "curry", and recipes besides.