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key - definition and synonyms

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noun [countable]     key pronunciation in American English
Word Forms
  1. 1
    a small piece of metal used for opening or locking a door or a container, or for starting the motor of a vehicle

    I could hear someone turning the key in the lock.

    a bunch of keys

    key to:

    Where’s the key to the back door?

  2. 2
    [usually singular] the thing that will do most to help you to achieve something
    key to:

    Proper planning is the key to success.

    The key to our strength lies in our members.

  3. 3
    one of the parts that you press on a keyboard to make it produce letters, numbers, etc.

    Highlight the file you want to open and press the ENTER key.

  4. 4
    music a set of musical notes that are based on one particular note

    a major/minor key

    a piece written in the key of C

  5. 5
    a list of signs and their meanings, for example a list of the signs that are used on a map, drawing, etc.
    1. a.
      a list of answers to the questions in a test or in a book
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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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