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1. and *under a deadline; *under the gun (about something) Fig. facing or enduring something such as pressure or a deadline. (*Typically: be ~; get ~.) I have to get back to work. I am under a deadline. I am under a lot of pressure lately. The management is under the gun for the mistakes made last year.
2. [of a gas or liquid] being forced, squeezed, or compressed. (*Typically: be ~; deliver something ~; put something ~.) The gas in the pipes leading to the oven are under pressure.
See also: pressure