Btvs Although this article is based on canonical information, the actual name of this subject is conjectural.
Willow Rosenberg[src]

Willow dissolving a binding field.

Solutum is an anti-binding field spell. This spell negated the effect of a binding field, freeing the caster. Once cast, the binding field immediately dissolves and disappears. The Latin incantation for the spell roughly means "soluble".

In 2002, Dark Willow used this successfully to free herself from Giles' second attempt to bind her. However, before she could do so, she failed several attempts to break free, trying several incantations like "Solvo" and "Libero", both roughly translating to "release" or "dissolve". Whether those incantations were simply incorrect, or they were weaker forms of the same spell as "Solutum" is unknown. Additionally, it may have been a stronger form of the dissolution spell.