In a space E equipped with a symmetric, differential k-form, or Hermitian form, the orthogonal sum is the direct sum of two subspaces V and W, which are mutually orthogonal. It is denoted V⊥W. More generally, V_1 ⊥V_2 ⊥...⊥V_n denotes a direct sum of subspaces of E which are pairwise orthogonal.

orthogonal complement | orthogonal decomposition