Is orthogonal nonsensical?

Even with ruler and compasses I couldn’t make sense of a remark I found on Twitter or X, as we all pleonastically call it. Someone had posted this observation: ‘One’s bank balance and number of children are orthogonal to social media usage.’ I knew the prefix ortho– meant ‘straight, perpendicular, right’. So orthogonal meant ‘right-angled’. But how could children be at right angles to social media usage?

I hadn’t cottoned on to the fashion for using orthogonal figuratively to mean ‘unrelated’, ‘irrelevant’. That is quite a stretch, for things at right angles are not unrelated. But there is no stopping orthogonal now, though the term seems unhelpful. It’s not even as though it were intended humorously, as happened to the learned term opisthognathous. Prognathous or jutting jaws are found in the popular idea of cavemen; an orthognathous profile has the brow and chin straight up and down; a receding chin is opisthognathous.