Etymology of ギリシャ: what language does "girisha" come from?


I have trouble remembering that
[Greece](https://www.wikipedia.org/wiki/Greece) is called ギリシャ.  
Understanding the etymology behind would probably help me?

What is the etymology of the word ギリシャ?  
What language(s) was the name inspired by?




The [Japanese
Wikipedia](https://ja.wikipedia.org/wiki/%E3%82%AE%E3%83%AA%E3%82%B7%E3%83%A3#.E5.9B.BD.E5.90.8D)
offers an explanation, unfortunately not backed by any reference:

> ギリシャあるいはギリシアという名称は、ラテン語名の Graecia （グラエキア）がポルトガル語で Grécia
> （グレスィア）となり、これが宣教師によって日本にもたらされ変容したとされる。

So it seems that the Latin name of Greece is `Graecia` became `Grécia` in
Portuguese, which in turn became what it is in Japanese when (Portuguese?)
missionaries visited.

