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1. Literally, forced through or into some vessel with great compressive force. The contents of this container are under pressure, so do no pierce it or expose it to fire or you could risk triggering an explosion. Crude oil underneath the ground can be under intense pressure, which is why it can erupt into a geyser when drilled into directly.
2. (While) facing or enduring a great amount of stress caused by some compelling or constraining influence. I can't talk now, I'm under pressure to get this done before the end of the day! Sorry, I'm just under so much pressure at work that it's made me rather irritable.
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.
1 if a liquid or a gas is kept under pressure, it is forced into a container so that when the container is opened, the liquid or gas escapes quickly
2 being forced to do something: The director is under increasing pressure to resign.
3 made to feel anxious about something you have to do: The team performs well under pressure.