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open - definition and synonyms

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verb     open pronunciation in British English
Word Forms
present tense
present participleopening
past tenseopened
past participleopened
  1. 1
    [transitive] to separate the edges of something, or to take off its cover so that you can see or remove what is inside

    She opened her shopping bag and took out an umbrella.

    Can you open this jam jar?

    Open your books at page 25.

    1. a.
      [intransitive] if something such as a flower opens, it moves into its widest position and you can see its full shape

      Her parachute failed to open.

  2. 2
    [transitive] to move a door or window into a position that allows people or things to pass through

    Do you mind if I open a window?

    The school gates are opened at 8.45.

    1. a.
      [intransitive] if something such as a door opens, it moves into a position that allows people or things to pass through

      The lift doors opened and two men walked out.

      open onto/into something:

      The kitchen door opens onto a patio.

  3. 3
    [intransitive/transitive] to move your arms or legs wide apart

    She opened her arms to hug me.

    1. a.
      to move your lips and teeth apart so that your mouth is not closed

      Open your mouth and let me look at your teeth.

    2. b.
      to move your eyelids apart so that your eyes are not closed

      I opened my eyes and looked around me.

    3. c.
      to make your fingers straight so that your hand is not closed
  4. 4
    [intransitive/transitive] if a shop, public building etc opens at a particular time, or if someone opens it, it regularly becomes available for people to visit or use at that time

    The library doesn’t open till 9.30.

    I’m calling to ask when you open today.

  5. 5



    open up

    [intransitive/transitive] if a new business, building etc opens, or if someone opens it, it becomes available for people to use for the first time

    They decided to move to Spain and open a bar.

    The college first opened in the 1960s.

    1. a.
      [intransitive/transitive] if something that has been private or secret opens, or if someone opens it to people, it becomes available for people to visit, see, or take part in
      open something to someone:

      There are plans to open the gardens to the public.

      open something to competition/inspection/scrutiny:

      The telecommunications market has been opened up to competition.

      open your doors/gates to someone:

      The farmer opens his gates to visitors during the lambing season.

    2. b.
      [intransitive] theatre, cinema if a film or play opens, it starts being shown to the public

      Her new play has just opened on Broadway.

    3. c.
      [intransitive/transitive] if a road, telephone line, or other method of communication opens, or if someone opens it, it becomes available for people to use

      We are opening a hotline for enquiries about the product.

    4. d.
      [transitive] if a famous person opens a shop or public building, they appear there to say that it is officially available for people to use or visit

      The Queen is opening the new gallery on Saturday.

  6. 6
    [transitive] to begin something such as a discussion or trial

    She opened the debate by summarizing her party’s position.

    open an investigation/inquiry/inquest:

    The police have opened an investigation into his business affairs.

    1. a.
      [intransitive] to begin a speech
      open with:

      He opened his talk with a quotation from Shakespeare.

    2. b.
      [transitive] to start an account with a bank

      You only need £1 to open an account with us.

    3. c.
      [intransitive] when a period of time opens, it begins

      The year opened well for the company.

phrasal verbs

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a form of location that involves the underwater detonation of a bomb which causes sound waves that are picked up by ships

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