What does depressurize mean?
Depressurize is a verb describing the loss or deliberate reduction of pressure within a sealed space such as an aircraft cabin, spacecraft, diving bell, or industrial vessel. It can be used transitively — engineers depressurize a pipeline before maintenance — or intransitively, as when a cabin suddenly depressurizes at altitude. Because uncontrolled depressurization is dangerous, the word carries strong technical and safety connotations, appearing most often in aviation reports, engineering manuals, and science fiction rather than casual conversation. It derives from the Latin root premere, meaning 'to press', via 'pressurize', with the negative prefix de- signalling removal or reversal. A useful related term is repressurize, describing the restoration of normal pressure after a loss event.
verbTo reduce or cause to lose air pressure or gas pressure, especially in an enclosed space such as an aircraft cabin, submarine, or sealed container. More generally, to relieve or release pressure of any kind, literal or figurative.
- To reduce the internal air or gas pressure of an enclosed space or vessel, often suddenly and unintentionally.
- To deliberately release pressure from a system as a controlled procedure.
"The pilot was forced to depressurize the cabin before making an emergency descent."
"Cabin crew donned oxygen masks when the aircraft began to depressurize at 35,000 feet."
"Engineers depressurize the pipeline slowly to avoid damaging the seals."
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of depressurize
Depressurize is formed from the prefix de- (indicating reversal or removal) attached to pressurize, a 19th-century English verb derived from 'pressure', which ultimately traces back to Latin premere, 'to press'. It emerged alongside modern aviation and pressurised-cabin technology in the early 20th century, though exact first-attestation dates vary by source. Cognate forms share the same Latin root across Romance languages, such as French pression and Spanish presión.
Related word forms
How depressurize is actually used
Chiefly used in technical, aviation, and engineering contexts. The intransitive form ('the cabin depressurized') and the transitive form ('they depressurized the cabin') are both common.
Easily confused with depressurize
Decompress broadly means to release pressure (or to expand compressed data), whereas depressurize specifically refers to losing or removing air/gas pressure from a sealed system.