Of two objects, at right angles; perpendicular to each other.
Of a square matrix: such that its transpose is equal to its inverse.
Of grid graphs, board games and polyominoes: vertical or horizontal but not diagonal.
Of two or more aspects of a problem, able to be treated separately; of a design, exhibiting consistency and composability.
Of a pair of vectors: having a zero inner product; perpendicular.
Of two or more problems or subjects, independent of or irrelevant to each other.
Of a pair of elements in an ortholattice: each less than or equal to the orthocomplement of the other.
Of a linear transformation: preserving its angles.
Statistically independent, with reference to variates.
An orthogonal line
Having axes that meet each other with right angles.
Having a shape like a rectangle.