Domain of influence
From Online Dictionary of Crystallography
Domaine d'influence (Fr). Wirkungsbereich (Ge). Dominio di influenza (It)
The domain of influence of a lattice point P (Delaunay 1933), or Dirichlet domain or Voronoi domain, consists of all points Q in space that are closer to this lattice point than to any other lattice point or at most equidistant to it, namely such that OP ≤|t - OP| for a any vector t belonging to the vector lattice L. It is the inside of the Wigner-Seitz cell.
Sections 126.96.36.199 and 188.8.131.52 of International Tables of Crystallography, Volume A, 6th edition