decompression

noun

1. (uncountable, usually)The process of decompressing.

   “The decompression of large data files may take a while.”

2. (uncountable, usually)The restoration to atmospheric pressure of a person who has spent time under higher pressure (such as a diver).
3. (uncountable, usually)A mode of operation of some internal combustion engines which reduces the engine's compression ratio, making it easier to start but significantly increasing fuel consumption.
4. (uncountable, usually)The relief of pressure on a body part by surgery.