They sure do. Colours are adjectives. Aside from a handful of invariable adjectives, you always need to change the ending of the adjective so that it agrees with the gender, number and case of the thing it's describing.
μπλούζα is a feminine noun. There's only one of it, and it's the subject of the sentence, so it's nominative singular.
In the singular nominative, green is: πράσινος in masculine, πράσινη in feminine and πράσινο in neuter.
So, we have μία πράσινη μπλούζα. If we were describing a green car - αυτοκίνητο - that's a neuter noun, so we'd have ένα πράσινο αυτοκίνητο. A green sky, sky being masculine: ένας πράσινος ουρανός.
In Wiktionary, most common words have declension tables, and you'll find yourself referring to them a lot!
Hope that helps a little.
Ι have no idea how romper got in there. It's not a correct translaton for 'μπλούζα', since it's technically something like a jumpsuit (a combination of shorts and a shirt https://en.wikipedia.org/wiki/Romper_suit )
However, while jumper and sweater are synonymous, there are better translations to πουλόβερ, rather than μπλούζα. If you google either sweater or jumper, the results mostly show knit (and long sleeved) garments, which is exactly what one would call πουλόβερ here.:/
Okay, thank you.
I feel like there are a lot of inconsistencies/mistranslations in the clothing vocab, unfortunately. Some of that is definitely false friends: Ζακέτα = cardigan catches me out a lot, because over here a jacket is a type of coat, and googling μπβλούζα just got me a lot of what I'd call T-shirts or polo shirts.
But some of the rest of it is genuinely confusing, such as the fact that σκούφι refuses to translate as 'hat' even though a cap is a type of hat (and I wouldn't call a σκούφι a cap in British English anyway - I'd call it a woolly hat or bobble hat, and I think Canadians would call it a toque. A cap is a cloth hat with a brim at the front, e.g. a baseball cap or a flat cap.)
Between the two problems, I know a lot of words and don't have a clue what articles of clothing they actually apply to :p The impression I'm getting is that Greek simply has a lot less words for articles of clothing than English does, and doubles up where we wouldn't - is that accurate?
I wouldn't say that Greek has a really limited vocabulary when it comes to clothing, at all. :P Yes, most words are borrowed from other languages, but we have quite a few of them.
The issue you're talking about is actually one of the English language, and not of the Greek one. We have gotten a lot of reports about clothing, because there are inconsistencies in clothing terms between American english and British english. This is why you probably keep getting some terms mixed up.
Here are some of the actual terms you've mentioned:
'Hat' translates to καπέλο, and just that
While 'cap' is a type of hat, there is a difference between καπέλο and σκούφος. Σκούφος is a knit winter cap, and no one would ever refer to it as a hat. (If you were talking about a simple cap, you'd still use καπέλο.)
Μπλούζα can refer to any type of shirt (usually a shirt with no buttons.) There are distinctions, like κοντομάνικη μπλούζα (short sleeved, but we do use the word t-shirt as well), μακρυμάνικη μπλούζα (long sleeved), αμάνικη μπλούζα (spaggetti or thicker strap.)
Ζακέτα is probably the most controversial one. It does mean 'jacket' (which is of course, something much lighter than a coat), but in english, jacket could also mean some type of coat, like let's say, a leather jacket. Ιn Greece though, there is no such thing as δερμάτινη ζακέτα. Jacket is ζακέτα (knit or not), and μπουφάν is the word for a thicker kind of coat (Μπουφάν is considered to be synonymous with παλτό, although I do consider μπουφάν thicker than παλτό).
Believe me, it's not as complicated as you think it is. We just had to incude some British english terms along with the American ones. When it comes to Greek, things are pretty straight and clear.