The word "orthogonal" means unrelated or independent. In mathematics, it refers to two things that are at right angles to each other, while in a general sense, it describes things that don't have any common or overlapping aspects. Full definition
The amplitude of the pattern defined by the leading empirical orthogonal function of winter monthly mean NH MSLP anomalies poleward of 20 ° N (Thompson and Wallace, 1998, 2000). (ipcc.ch)
Including them means that a large number of orthogonal functions would be needed, and that would in turn produce potentially very strange and totally wrong artifacts over oceans. (judithcurry.com)
In Orthogonal Frequency Division Multiplexing (OFDM), frequency offset is a common problem that causes inter-carrier-interference (ICI) that degrades the quality of the transmitted signal. (semanticscholar.org)