Someone who catches wild animals with traps, nearly always for their fur — beaver, fox, mink, marten. The word carries a strong historical picture with it: the North American frontier, men who spent winters alone in the forests of Canada and the northern United States, checking a line of traps and selling the pelts. That fur trade shaped a lot of North American history, and "trapper" belongs to that story more than to modern life. Trapping still happens, and there are still people who would call themselves trappers, but the word now sits in an argument — many people see it as cruel, some see it as a traditional livelihood, and it is a genuinely live disagreement rather than a settled one. There is also a plainer, smaller use: someone whose job is to trap pests, though that person is usually called a pest controller instead. If you see "trapper" in a modern game or film, it is usually the frontier image being borrowed.