Unicity refers to various things.

Unicity Distance of Robust Image Hashing
On the unicity of dempster rule of combination
Unicity theorems for meromorphic or entire functions. II.
Unicity of the equilibrium in the unconstrained Hotelling model
On the Unicity of the Homotopy Theory of Higher Categories
A unicity theorem for entire functions concerning differential polynomials
Unicity in an inverse problem for an unknown reaction term in a reaction-diffusion equation
On the existence and unicity of solutions of stochastic integral equations
Fractals in physics: Squig clusters, diffusions, fractal measures, and the unicity of fractal dimensionality
Rostral Cingulate Zone and correct response monitoring: ICA and source localization evidences for the unicity of correct- and error-...