A shee (pronounced /ʃiː/) is a landmass separate from any other landmasses or bodies of water or other liquid, instead surrounded on all sides (including top and bottom) either by gaseous substance or by complete emptiness. It is usually also considered a necessary part of the definition of a shee that its immediate surroundings have a well-defined gravitational direction, that there exists an "up" and a "down" on the shee. (If the shee is near a larger mound, this gravitational direction usually, though not necessarily, matches that of the mound; "down" on the shee is the same direction as "down" on the world below.) A landmass may still be considered a shee if bodies are gravitationally drawn to two opposing sides, but not if gravity simply operates radially toward the shee's center, or if the shee exerts no significant gravitational force at all. Thus an asteroid, for example, would not usually be considered a shee, even though it meets all the other criteria. Technically, a landmass with any rigid connection to a surrounding world is not a shee, no matter how narrow or tenuous that connection may be. However, a landmass connected to a neighboring mass by a link clearly too thin to actually offer appreciable support has much in common with a shee, and is often called a semishee, or sonshee.
Shees may be found floating in the skies above a world, but may also be found floating in the space between worlds, or in other large voids. Shees are often, but not always, flat on the top (assuming there is a top, which of course may not be the case in a plane without gravity.) They may be nothing more than huge barren rocks, but they may also be covered in vegetation and animal life.
Shees are sometimes called floating islands, but this term is ambiguous, as it can also refer to an island that literally floats on the top of an ocean or another body of fluid. A particularly large shee is known as a wolk.
A number of natural processes may give rise to shees. On many worlds, shees arise because of spontaneous enchantment, some feature of the local arcanum bringing them into being. The effect of this enchantment may depend on other circumstances, so that the fact that shees exist on one world does not necessarily mean they must also exist, or exist in the same numbers, on another world where the same arcanum is active. Shees may also exist due to physical causes: because they are filled with lighter than air minerals or gases, or with substances that oppose gravity such as antite in Ses. They may also be suspended by magnetism or other repulsive forces, or for that matter attractive forces if they're attracted to surfaces above them, or the nature of gravity on the worlds where they are located may be such that no additional forces are necessary to hold them in place.
By no means are all shees natural, however; many shees are of artificial origin. They may be suspended by magic, or by feats of engineering that keep them in flight. A disadvantage of some artificial shees, however, is that they require constant power to keep them in position—either continual renewal of the enchantment, or fuel for whatever physical process keep them up. Should the forces maintaining the shee fail, the shee may end up plummeting to the ground... with dire consequences both for whoever and whatever may be on the shee at a time, and also for the contents of the ground it falls onto.
In any case, such artificial shees may be created by single powerful individuals, or by individuals with little personal power but access to talismans or technology that is up to the job. Probably more often, however, they are the creation of groups or organizations working together to make them. Whoever is responsible for their creation, artificial shees are obviously made for a specific purpose, and often serve as a home or base for their creators. This is not to say, though, that they may not be later taken over for other purposes, or even that, if they do not require a dwindling power source, they may long outlast their creators and float, abandoned or resettled by others, years after their original creators are gone and they no longer serve their first purpose.
Some shees are immobile, hanging in the same place perpetually. Others, however, are in motion, either continually or intermittently. Of course, to define a shee's motion it is first necessary to specify what the motion is being measured relative to. If there is a larger shee, a mound, or some similar large landmass nearby, it is relative to this larger mass that the motion of the shee is most naturally measured. If not, it may be measured relative to the surrounding gas, if any. This latter may lead to some ambiguity if the gas itself has currents in different directions in the shee's vicinity, or if the gas is itself moving relative to a large nearby landmass, but these cases are relatively rare.
Mobile shees may move due to the same forces that keep them suspended, or due to other, independent causes. In the latter case, of course, the sent's motion may be disabled independently of its suspension—or possibly vice versa. Some shees move along fixed patterns, including continual motion with a fixed velocity; other shees meander randomly, though possibly remaining within a set area. The motion need not be entirely lateral; shees may move up and down as well, and may change their speed as well as their direction. In a world with multiple shees in motion, collision between shees is a real possibility, and one of which residents of those shees are likely to have taken measures to minimize the effects.
Shees are commonly made of the same material as the nearby world, if any. Generally, this means earth and rock, though shees near exotic worlds (and some solitary shees with no worlds nearby) may be made of more unusual materials. Natural shees are typically made of the same materials as nearby worlds because they were formed by the same processes. In the case of artificial shees, however, the extra material must come from somewhere. It may be torn from the world itself, which is likely to leave some scarring (though scarring that may later be effaced by erosion and other processes). It may also be created ex nihilo, however, or transmuted from other available substances, or translocated from other worlds or planes.
Many shees are made of materials entirely different from any nearby worlds, however. Shees resembling clouds are fairly common; artificial shees are often designed with this appearance to disguise them from easy notice from below (as long as spectators don't notice the clouds' unusual motion or persistence), but on some worlds clouds naturally solidify into shees. Other shees may be formed of glass, of metal, of ice, of crystals, or of nearly any other substance.
Shees are commonly flat on the top, and more irregular and craggy on the bottom. This is by no means a necessary feature, though, and many shees do not conform to this description.
The development of life on shees, where there is a larger, life-bearing landmass nearby, follows similar lines to that on islands. Shees may start out barren, but eventually various species will colonize it and thrive. Over time, their isolation will tend to cause them to evolve into forms different from those on the "mainland"; perhaps, absent the predators that plagued their ancestors, they may become smaller, or lose some of their defenseive abilities. One thing that makes the development of life on a shee different from that on a normal island is the shee's greater isolation; there are fewer life forms that can cross an expanse of gas or void than there are that can swim or float across an ocean. Still, some flying organisms may land there, only for their descendents to later lose the ability of flight that brought them there, and some small or light organisms may somehow be brought to the shees by other means—some types of plant seeds blown by wind being a notable example. Therefore, while the biological diversity on a shee may be even smaller than that on an island, at leats after a comparable amount of time to develop, life is still likely to find a foothold there.
On isolated shees far from any life-bearing world, life is not likely to arise unless through spontaneous generation, or unless introduced artificially. There are, however, ways for life to colonize even these worlds. There may be life within the very void wherein the shee floats that can colonize it. Travelers may accidentally introduce species that infest their vessels or even their persons. And, of course, some species with natural abilities of long-distance translocation, or even interplanar travel, may be able to colonize such worlds regardless of how far they may be from their former habitats.
Artificially created worlds are often likewise artificially stocked, their creators populating them with flora and fauna according to their desires. Even then, however, other life forms may end up adventitiously colonizing the shee that their creators didn't anticipate, possibly displacing the life forms that are supposed to be there. If they're still around, the shee's creators or current residents may be forced to fend off the invasive species—or to simply accept the changes they wreak in the ecosystem.