de·com·pres·sion (d??k?m-pr?sh??n)n.1. The act or process of decompressing.2. A surgical procedure used to relieve pressure on an organ or part, such as the abdomen, cranium, or spinal cord.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.de?com?pres?sion (?di k?m?pr?? ?n) n. 1. the gradual reduction in atmospheric pressure experienced after working in deep water or breathing compressed air. 2. the act or process of releasing from pressure or stress. 3. a surgical procedure for relieving increased cranial, cardiac, or orbital pressure. 4. Computers. the restoration of data that has undergone compression to its original state. [1900?05] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.decompressionA method of removing or relieving pressure, such as by opening the skull to relieve pressure that has built up inside it.Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited