People often ask where the terms "Marauders" or "Raiders," commonly used by Harry Potter fans, came from. Here is a brief explanation. (The former was the translation used by Taiwan's Crown Publishing, while the latter is the more common translation in fanfiction.)
The word "Marauder" came from the Marauder's Map. People's Literature Publishing House translated it as "Marauder's Map," while Taiwan's Crown Publishing translated it as "Raiders' Map." (In the original books, James, Sirius Black, Remus, and Peter never called themselves the Marauders. Rowling later confirmed on her official website that the four had indeed given themselves the title of Marauders, and thus named the map after it.)
Literally, "Marauder" means "bandit," "robber," or "raider"—someone who roams about looking for opportunities to steal or loot.
The term "Marauder's Map" was presumably a deliberate liberal translation. After all, the original was not difficult to translate from the text, so there was no need to invent a new term and rename the map, making translation more difficult. Thus, the only possible conclusion was that the publisher did not want to use the original wording. A literal translation would have made it something like "Robbers' Map" or "Raiders' Map," which was obviously unsuitable for a thirteen-year-old audience.
However—"marauder" could also refer to a predatory animal roaming about.
Neither "Raiders" nor "Plunderers" was correct. When James and the others designed this map:
First, the four of them used animals as code names.
Second, the group's purpose was to roam around and break school rules, not to rob or plunder!
From this, it could be seen that the implication behind their choice of "Marauder" was "roaming predatory animals." Here, "predatory" could metaphorically refer to seeking opportunities to break school rules—or, one could say, searching for secret passages and uncovering the castle's secrets. Therefore, when translating the name of this group, meanings such as "roaming," "wandering," and "sneaking" should take precedence over meanings like "plundering" or "stealing." (Unless, of course, a fanfiction author was specifically writing James as a villain; then that would be another matter.)
In this book, the author translated "Marauder" as "Marauder."