The following terms, and the given information about them, are known by all player characters in the Worlds of Adventure campaign (after they've become commissioned adventurers with the Argos Trade Consortium).
adventurer: A person who goes on dangerous quests, usually as part of a small group. Adventurers usually operate outside the bounds of militaries, religious organizations, or any other large-scale social structures; they most often work "freelance", pursuing their own personal goals, temporarily doing things for other people or organizations when it suits them. (May also specifically refer to commissioned adventurers working on contract with the Argos Trade Consortium.)
Argos Trade Consortium: An interdimensional organization of traders, based in the City, whose members travel between worlds via the Gates. Also known as the A.T.C. or the Consortium. Notable for recruiting adventurers, whom the A.T.C. trains in combat and magic, in exchange for the adventurers acquiring treasure on the A.T.C.'s behalf. See The Argos Trade Consortium (A Worlder's Perspective)? and The Argos Trade Consortium (An Adventurer's Perspective)? for more information.
A.T.C.: See Argos Trade Consortium.
citizen: A permanent resident of the City. It is not clear whether most citizens are native to the City, whether they built the City, or indeed anything about who they are and where they come from (although it does seem that at least some citizens are former worlders). Citizens appear for the most part to be members of the common races. Most (all?) citizens work for the Argos Trade Consortium. (See worlder.)
City, the: The fantastic extradimensional (?) metropolis that is the home base of the Argos Trade Consortium. The actual location of the City, in physical or planar terms, is unknown. Connected by standing portals called "gates" to many other worlds and realms. See The City for more information.
common races: Humans, elves, half-elves, half-orcs, gnomes, dwarves, and halflings. Members of these races make up most of the populations of civilized nations on most worlds with which the A.T.C. conducts trade, and from which adventurers (including the player characters) are recruited.
Consortium, the: See Argos Trade Consortium.
gate: One of many magical portals that connect the City to other worlds and realms. Often capitalized ("the Gate") when speaking of the single A.T.C. gate on a given world. Can be activated or deactivated. Not to be confused with the gate spell, which creates a temporary portal between planes. See The Gate for more information.
gatespeak: The colloquial form of Interlang spoken by most adventurers, full of slang and idiomatic expressions borrowed from the Common tongues of a dozen worlds. See also Interlang.
Interlang: A language invented by the Argos Trade Consortium, and taught to worlders whom the A.T.C. recruits to be adventurers. Very similar to the Common tongues of most civilized worlds. Most worlders find Interlang very easy to learn, and knowing it makes it much easier to communicate with people from different worlds (see the Linguistics skill description for more information). See also gatespeak. "Interlang" usually refers to the formal, linguistically pure form of the language used by A.T.C. officials and other citizens, while "gatespeak" refers to the colloquial, slang-ridden dialect of Interlang spoken by adventurers and other worlders who work with the A.T.C.
realm: Any plane of existence, planar layer, world, planet, or other roughly self-contained domain in any of the multiverses or dimensions reachable via the Gates. Many realms have unique environmental and magical properties.
world: Any one of the many worlds accessible via one of the A.T.C.'s gates. Usually refers to spherical planets, the surfaces of which are habitable, and inhabited, by members of the common races (but not always; see e.g. Mystara?). Most worlds are on the Prime Material Plane of their multiverse. (See also realm.) Characters who come from a world contacted by the Argos Trade Consortium (as opposed to being native to the City) are known as worlders.
worlder: A person who hails from one of the worlds contacted by the Argos Trade Consortium. All (known) adventurers, including the player characters, are worlders. (See citizen.)
These game terms are unique to the Worlds of Adventure campaign, or are used in novel ways here.
character level: A measure of a character's overall power level. Character level is determined by how much XP a character has spent to gain levels in one or more classes. (See What Level?? for more information.) Note that a character has as many hit dice as his character level.
class group: One of four groupings of character classes: warriors, mages, priests, and rogues. (See Character Advancement for more information on class groups.)
class progression: All of the class levels that a character has in a particular class group. (For example, a character's mage class progression is all of his wizard, witch, and sorcerer class levels put together.) Each character has a primary class progression (all of that character's levels in classes of the first class group the character started with), and might have one or more secondary class progressions. (See Character Advancement for more information on class groups and progressions.)
cross-classing: Taking levels in classes from different class groups. (The cross-classing system is unique to the Worlds of Adventure campaign.) For example, when a character with levels in one or more warrior classes decides to take levels in a mage class (say, wizard), he uses the cross-classing rules. (See Character Advancement for more information on cross-classing.)
hit dice: The more hit dice a character or creature has, the more powerful they are, generally speaking. A character has as many hit dice as his character level. Each hit die grants a character some number of hit points, depending on class and Constitution score. Some magical effects use hit dice to determine whether they can affect a creature.
item level
mage: A character who's a member of the mage class group (which includes the wizard, sorcerer, and witch classes).
multiclassing: Taking levels in different classes within the same class group. (The multiclassing system in Worlds of Adventure is almost the same as the multiclassing rules used in Pathfinder and similar game systems.) For example, when a character with levels of fighter decides to take levels of barbarian (both of which are warrior classes), he uses the multiclassing rules. (See Character Advancement for more information on multiclassing.)
priest: A character who's a member of the priest class group (which includes the cleric, druid, and mystic classes).
rogue: A character who's a member of the rogue class group (which includes the thief, bard, and ranger classes).
warrior: A character who's a member of the warrior class group (which includes the fighter, barbarian, and monk classes).