Pronunciation: (ôr-thog'u-nl),[key] —adj. 1. Math. a. Also,orthographic.pertaining to or involving right angles or perpendiculars: an orthogonal projection. b. (of a system of real functions) defined so that the integral of the product of any two different functions is zero.
c. (of a system of complex functions) defined so that the integral of the product of a function times the complex conjugate of any other function equals zero.
d. (of two vectors) having an inner product equal to zero.
e. (of a linear transformation) defined so that the length of a vector under the transformation equals the length of the original vector.
f. (of a square matrix) defined so that its product with its transpose results in the identity matrix.
2. Crystall.referable to a rectangular set of axes.