An invariant definition of the operator $\Delta $ of the Batalin-Vilkovisky formalism is proposed. It is defined as the divergence of a Hamiltonian vector field with an odd Poisson bracket (antibracket). Its main properties, which follow from this definition, as well as an example of realization on K\"ahlerian supermanifolds, are considered. The geometrical meaning of the Batalin-Vilkovisky formalism is discussed.
