A previous author has already used/created the name of a group of people in a (seemingly not very popular) fiction novel about 2 years ago. Can I use the same name for a different group of people in my (completely different) book, or would it be a copyright infringement? Thanks.
Dodgy ground. I know that for popular and well known works, fictional races are strongly protected. Try to write a book with "hobbits" in it and the Tolkien estate's lawyers will crawl out of your USB port before you can even hit the save button. Likewise, the FASA game company released a combat game ages ago. The first name was "Battledroids", but George Lucas's lawyers had a word with them, and they changed it to "Battletech." However, I don't know if those were based on copyright or trademark law.
That is very dodgy ground you're talking about, indeed. I would play it safe and just come up with your own name. You don't want to take the chance of having lawsuits pending over something as little as that.
Europans has been used by Arthur C. Clarke in 2010 and 2061, but he was using that word in reference to natives of the Jovian moon Europa, which makes the term about as trademarkable as "Martians" (or Jovians, for that matter), so I think you'd be on pretty clear ground if it related to that moon. It also sounds generic enough that you should be okay, it's not like you're referring to them as Braxana or Muggles or anything completely created out of thin air. ETA: A quick Google shows that the term has been used by Ernest Cline, who wrote Ready Player One, as well as by someone named Ralph A. Gilson, and a Mr. James Press. So, it's clearly not like Hobbits, but if it's not the name of natives of that moon, do you really want to risk your critters being confused with the creations of not one, but four other authors, two of whom have a certain name recognition factor already?
I see. Nice work. So there could be some confusion, but you're saying it's legal, especially if more than one author has used it already? And why would one author use it, followed by several others? Why wouldn't they want to create their own if fearing copyright infringement?
I don't know if it's possible to copyright a single word unless it's part of a logo or a company identity. And even then, I suspect there's more to it than simply copyrighting the word(s) itself. (For example: International Business Machines - only when the three words are used together do they become part of IBM's intellectual property.) But that's all beside the point, really. 'Europan' is defined as 'of or pertaining to Europa, a moon of Jupiter.' To me, that's like using the word 'Terran' to describe someone from Earth. Anyone can use the word. On another note... if you're not using 'Europan' to describe someone (or something) from Jupiter's Europa, there may be confusion in the minds of readers.