The Nisnevich topology, also called the completely decomposed topology, is a certain Grothendieck topology on the category of schemes which is finer than the Zariski topology but coarser than the étale topology. It retains many desirable properties from both topologies: The Nisnevich cohomological dimension (and even the homotopy dimension) of a scheme is bounded by its Krull dimension (like Zariski) Fields have trivial shape for the Nisnevich topology (like Zariski) Algebraic K-theory...