Adventurers

In some fantasy settings, the term "adventurer" is a meta-descriptor for certain types of characters but is not used in-universe. In other settings, an "adventurer" is a professional who must join a guild and execute a career in a highly structured and formalized role in society.
Nexus lies somewhere between these two extremes.

What Is An Adventurer?

The mortal peoples of Nexus do indeed use the term "adventurer." It's a colloquial term with a commonly understood meaning, not a formal title for a well-defined career. An adventurer is considered to be a sort of freelance problem-solver, and is assumed (whether individually or as part of a team) to be capable of accomplishing an array of objectives, ranging from monster-hunting to mystery-solving. Sometimes these gigs are offered to adventurers in exchange for pay, while at other times a "job" might be something the adventurer pursues on their own initiative due to a possibility of incidental benefit (such as renown for good deeds or treasure which may be discovered in a dungeon).
Activities typically associated with adventuring include slaying or pacifying a monster that's harrying a town, venturing into a dangerous area to retrieve goods for a buyer, or exploring a dungeon or other remote location in search of treasure, information, or items of personal interest. In addition to this type of work, an adventurer's gig-based lifestyle often pushes them to develop a diverse portfolio of skills that qualifies them for similar work that can also be handled by non-adventurers—caravan guards, private investigators, and so forth. Rookie adventurers in particular often take such jobs to fill gaps between "true" adventuring gigs, while more experienced and renowned adventurers rarely have much need of these side jobs.

Adventurers In Society

For the most part, people have a net-positive view of adventurers. They serve an important social role as problem-solvers, whether for hire or in response to a crisis. Furthermore, successful adventurers often help economies by receiving payment from the wealthy (whether for services performed or by selling rare treasures) and then spending that money on lower- and middle-class goods (such as food, lodging, and equipment). Finally, there are historical examples of powerful adventurers being able to intervene directly against exploitive regimes or chaotic threats.
That said, most people also have a healthy sense of caution toward adventurers as well, especially those who haven't built a reputation yet. It's not unheard of for bandits or pirates to operate under the guise of being "adventurers," trying to see how much they can get away with before they draw some heat and skip town. Conversely, real adventurers tend to grow rapidly in power (if they don't die), which sometimes results in a shift in mindset toward using that power for domination and exploitation. It's not unheard of for ex-adventurers to become villains who are then taken down by other adventurers.
The balance between these two facets of adventurers can vary by location or even from person to person. A town that was saved by a team of adventurers will tend to have a more positive view, someone exploited by frauds will likely be sour toward adventurers, and large cities who see lots of adventurers pass through might not care too much one way or the other.