Strength of nations
Arbyr is a multipurpose word amongst most casterway cultures. It derives from the Komon word for tree, but it would be overly simplistic to imply that arbyr = tree. Being generally a forested planet, trees command a central presence in most of Excilior's civilizations. Not only do they dominate the landscape, but they have been central factors in habitation and construction. As such, many cultures coalesced upon the term arbyr to refer to those specimens that are particularly large, particularly impressive, or have somehow played a central role in their societies.
Many cities - especially those of Tallonai or Elladoran origin - are centered upon a single, massive tree. This tree is typically a canopeia, but there are other species of grand stature that can also fit the bill. These trees come to represent far more than plant life. They are, in a very literal sense, the essence of the society itself. When cities have been raided by foreign armies, the primary focus of those armies is not to destroy a castle, or a city hall, or the local klyster. Their first objective is to fight their way to the city center and burn those peoples' arbyr to the ground. A military defeat of this nature is one of the most humbling that a culture can absorb.
HeritageAs long as that tree stands, the population will typically transfer their culture, in spirit, upon it. In this sense, people may use the word arbyr nearly as a replacement for heritage. Someone may say, "They have undermined the arbyr of our lands." Or, "I give this to you as a symbol of our arbyr."
LoricsIn most societies, the arbyr actually serves as a written, semi-permanent record of those who have lived and thrived there. This happens because the names of the arbyrkin and, to some extent, their accomplishments, are actually carved into the base of the arbyr itself. These engravings start low near the arbyr's base and slowly move up the trunk over time. In this way, one can read an account of the arbyr's history in chronological order as they move upward (assuming they can scale high enough to continue their research). In some communities, these records are simply the names of those who hail from this arbyr. But in others, the engravings include detailed (supposedly) historical accounts of the adventures and travails of the arbyr's residents. Cognoscenti have often been able to use these carvings to verify (or debunk) ancient accounts and legends. Whether the engravings are "just" names, or whether they go into much more detail, they are always referred to as lorics and those tasked with maintaining and extending the engravings are called loricists.
In the nations of Islemanoton and western Islegantuan, as well as nearly all muddwood regions of the world, habitation in trees is both practical and common. With this in mind, the idea of an arbyr takes on a general meaning of community.
NeighborhoodIn this sense, arbyr never refers to a single household, because the epic trees leveraged for housing usually accommodate dozens - or hundreds - of souls. So a single tree can easily be equivalent to a city block or an entire village, in terms of the people that it supports. The residents of such trees often speak of arbyrs. But when they refer to the arbyr, they're often speaking more about the community than they are about the tree itself. In this parlance, it's typical to hear someone say, "We need to look out for our own arbyr." Or, "You shouldn't be wasting your time with people from that arbyr." Used in this way, these sentences aren't referring, literally, to trees. They're talking about the communities and neighborhoods that are tied to those trees.
Given that arbyr can reference an entire community, there are times when the community being discussed is completely, or mostly, from a specific family line. In this case, arbyr can be a reference to the whole family. But arbyr is never used to refer to a small family unit - like, two parents and their immediate children. If someone is speaking of their family as an arbyr, they're speaking about their entire family - aunts & uncles, grandparents & great-grandparents, cousins, nieces & nephews - everyone. Usually, this even implies those who are long dead. So in other words, arbyr can mean "an entire family line - past, present, and future". In this respect, someone might say, "Special care was taken with her, for she was the last of our arbyr." Or, "I didn't care much for my cousin, but I couldn't stand by while someone was attacking our arbyr."
Character or Constitution
Metaphorically, humans are fond of extending the strength of the great trees to themselves. This means that they portray "strong", or generally-favorable traits, as being indicative of someone's arbyr. In this sense, arbyr can be analogous to character or constitution. It would be natural to hear someone say, "I wasn't shocked to see him break his word because his arbyr has always been suspect." Or, "She was gravely wounded but I wasn't worried, for she has the strongest arbyr that I've ever seen."
Just as arbyr can refer to one's community, arbyrkin are those individuals in the community whom one can count on to stand behind them. They are allies - but not simply allies by treaty or by rote duty. They are allies due to a perceived bond or obligation that goes beyond political ties. Arbyrkin are often the close individuals who were raised in the same community (arbyr) and now feel an obligation of honor and brotherhood to support each other going forward. These aren't necessarily people from the same community. They could be extended family from other regions. They could be people who fought side-by-side in previous battles/wars and now feel connected. They could be separate family lines that have nonetheless backed each other over centuries.
BrotherhoodWhatever the underlying reason, when someone identifies another as arbyrkin, they are implying a kindred connection that is deeper than just, "We come from the same place." They're implying that, "We stand behind each other, and we'll fight for each other if need be." At the lowest level, this could be equivalent to "my fellow gang members." And at the highest level, it could mean, "my fellow patriots," or, "the members of my Order." When someone applies to the Ascendant Council to become an aspirant and participate in the Ascension Rite, they must bring 98 arbyrkin with them. Those arbyrkin are not there merely for show. If the candidate is accepted as an aspirant, the arbyrkin will be expected to fight - to the death - alongside the aspirant, and on their behalf.