Ether Lump

Ether, the Fifth Imaginary Substance as coined by the Association. It is a necessary medium that gives shape by mixing with the Four Elements.
It is shapeless, but it is a critical element in the functioning of magecraft.
Ether is bound to become one of Earth, Water, Fire and Wind, but in the hands of a novice, it would fail to become one of the Four Elements and materialize. This is ether lump.
Ether lump is completely useless. In some sense, creating ether lump is analogous to creating “Nothingness.” Looking at it from this perspective makes it sound like “True Magic” In fact, ether lump is originally the First Magic's———

Garden of sinners Pamphlet: Kara no Kyoukai Settings Glossary