Deflationary is the adjective for something that pushes an economy toward deflation: less money moving around, prices falling or stuck. A government that cuts spending very hard, or a central bank that makes borrowing very expensive, can be called deflationary. You will meet it in news about money — deflationary policy, deflationary pressure, a deflationary spiral — almost never in daily chat. It describes a force or a policy, not a person. Do not use it for a tyre; a tyre that has lost air is deflated, not deflationary.