stay up until a particular time meaning

• [American slang]
  to remain awake and out of bed until a particular time.
    I stayed up until long past midnight last night.
    Do you think Susie should stay up until midnight?

• time until expiration:    [Finance]The time ...
• stay up:    Verb: stay upNot g ...
• keep sth until some time:    [American slang]to ...