de ‧ com ‧ press /ˌdiːkəmˈpres/ BrE AmE verb [transitive]
1 . to reduce the pressure of air on something
2 . technical to change the information in a computer document back into a form that can be easily read or used, when the information was stored on the computer in a special form that used less space in the computer’s memory:
Most Macintosh computers can decompress files automatically.
—decompression /-ˈpreʃ ə n/ noun [uncountable]