deflate

Concise Oxford English Dictionary © 2008 Oxford University Press:
deflate/dɪˈfleɪt/

▶verb

• 1 let air or gas out of (a tyre, balloon, or similar object).

  ■ be emptied of air or gas.

• 2 (usu. as adj. deflated) cause to feel suddenly dispirited.

• 3 Economics reduce price levels in (an economy).

– derivatives
deflator noun.

– origin C19: from de- + -flate (as in inflate).