Synonyms for Orthogonal (same or very similar meaning)
WordNet sense 1 (not pertinent to the matter under consideration):
extraneous, immaterial, impertinent
WordNet sense 2 (having no bearing on or connection with the subject at issue):
irrelevant
WordNet sense 3 (lacking a logical or causal relation):
unrelated
WordNet sense 4 (having a set of mutually perpendicular axes; meeting at right angles):
rectangular
From the ODE community, based on WordNet
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