Shrinkflation
Etymology
A portmanteau of "shrink" and "inflation," often credited to the economist Pippa Malmgren, who popularized it around 2009–2015. The coinage does the explaining: the product shrinks while the effect is inflationary. It caught on as consumers noticed emptier chip bags and thinner rolls during periods of rising costs.
noun · /SHRINGK-flay-shun/
Reducing the size or quantity of a product while keeping its price the same, so buyers pay the same for less.
What it names
A precise handle for a stealth price increase that hides in the packaging rather than the price tag — the reason your favorite snack got smaller without getting cheaper.
Example
The cereal box is the same height but two inches thinner — pure shrinkflation.
Related idea
Skimpflation is the quality-cutting sibling: instead of less product, you get the same amount made with cheaper ingredients or less service.