Nullity refers to the state of being null or void, meaning that something has no legal effect or validity. In legal contexts, a contract or agreement may be declared null if it lacks essential elements, such as consent or lawful purpose. This means that the agreement is treated as if it never existed. In mathematics, nullity can describe the dimension of the kernel of a linear transformation. Specifically, it indicates the number of solutions to a homogeneous equation, providing insight into the properties of the transformation. Understanding nullity is crucial in fields like linear algebra and functional analysis.