Degenerate rune
From Delgar
Degenerate runes are runes which are incomplete, lacking either a sink or a font. Runes which possess both a sink and a font but lack any other structure are sometimes considered degenerate, but academic analysis traditionally describes such runes as simply uncoordinated rather than degenerate.
By far the most well-known degenerate rune is Skeld, which is used primarily for its side-effect of absorbing an arbitrary amount of power via its unbounded sink, which has the effect of controlling aethersickness.
In academia, degenerate runes are most often encountered in the domain of runic synthesis, though such techniques became largely a lost art following the chaos wars.