Learn how to say Unpressurised correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word unpressurized:
(of a gas or its container) not having raised pressure that is produced or maintained artificially:
in unpressurized air, the vapour levels were too low to trigger a serious fire
(of an aircraft cabin) not having normal atmospheric pressure maintained at a high altitude:
the unpressurized rear fuselage