Orthogonal

(geometry) Of two objects, at right angles; perpendicular to each other.
(mathematics)

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.

(statistics) Statistically independent, with reference to variates.
(software engineering) Of two or more aspects of a problem, able to be treated separately.
Of two or more problems or subjects, independent of or irrelevant to each other.