de·com·pres·sion / ˌdēkəmˈpreshən/ • n. a release of compressing forces, in particular: ∎  reduction in air pressure. ∎  a gradual reduction of air pressure on a person who has been experiencing high pressure while diving, in order to prevent decompression sickness. ∎  the process of expanding computer data to its normal size so that it can be read by a computer. ∎  a surgical procedure that relieves excessive pressure on an internal part of the body such as the spinal cord.

decompression (dee-kŏm-presh-ŏn) n.
1. the reduction of pressure on an organ or part of the body by surgical intervention. Raised pressure in the fluid of the brain can be lowered by cutting into the dura mater; cardiac compression – the abnormal presence of blood or fluid round the heart – can be cured by cutting the pericardium.

2. the gradual reduction of atmospheric pressure for deep-sea divers. See compressed air illness.

decompression Returning a compressed image or compressed data to its uncompressed form. Some compression methods lose information so that the uncompressed image or data is not equivalent to the original.