Comment by thelamest

This is not the common definition (cf. https://en.wikipedia.org/wiki/Inflation), but a narrower one (https://en.wikipedia.org/wiki/Monetary_inflation). Semantic difference, but one that remains a little confusing and harkens back to old economic debates. Focusing on policy causes of price changes is preferred among authors who want to tie inflation only/mostly to central bank actions, but mainstream economics, with Friedman etc., works with a slightly wider model (money supply is a key lever, but other things matter as well).