Calling all Wordsmiths: What is it called when there is the same or similar word in two different languages with totally different meanings (see details)?

For example, “eclectic” in English means a variety of things from a diverse range of sources, whereas the same word in Greek, eklektikos, means something of superior quality. There are a lot of the same words in Swedish and Danish, but with totally different meanings as well. These words cause a lot of confusion. There is a word for this, but I can’t remember what it is and don’t know where to go to find it.