But using exponential to mean a linear equation is all sorts of wrong, even in a colloquial sense. I would understand a colloquial meaning of "exponential" as

But using exponential to mean a linear equation is all sorts of wrong, even in a colloquial sense. I would understand a colloquial meaning of "exponential" as "it grows faster than linear". Wrong, but it makes informal sense. But using is as a synonym for linear makes no sense whatsoever.