orthogonal

Of two objects, at right angles; perpendicular to each other.

Of a pair of vectors: having a zero inner product; perpendicular.

Of a square matrix: such that its transpose is equal to its inverse.

Of a linear transformation: preserving its angles.

Of grid graphs, board games and polyominoes: vertical or horizontal but not diagonal.

Of a pair of elements in an ortholattice: each less than or equal to the orthocomplement of the other.

Statistically independent, with reference to variates.

Of two or more aspects of a problem, able to be treated separately; of a design, exhibiting consistency and composability.

Of two or more problems or subjects, independent of or irrelevant to each other.