Definition of jack noun from the Oxford Advanced Learner's Dictionary

     

    jack

     noun
    noun
    BrE BrE//dʒæk//
     
    ; NAmE NAmE//dʒæk//
     
    Motoring problems and accidents, Children's games, Devices
     
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  1. 1 [countable] a device for raising heavy objects off the ground, especially vehicles so that a wheel can be changed See related entries: Motoring problems and accidents
  2. 2[countable] an electronic connection between two pieces of electrical equipment See related entries: Devices
  3. 3 [countable] (in a pack / deck of cards) a card with a picture of a young man on it, worth more than a ten and less than a queen the jack of clubs Wordfinderace, card, cut, deal, gambling, hand, jack, shuffle, suit, trump
  4. 4[countable] (in the game of bowls) a small white ball towards which players roll larger balls
  5. 5 jacks [plural] a children’s game in which players bounce a small ball and pick up small metal objects, also called jacks, before catching the ball See related entries: Children's games
  6. 6(also jack shit taboo) [uncountable] (North American English, slang) (usually used in negative sentences) anything or nothing at all You don't know jack.
  7. see also blackjack, flapjack, Union Jack
    Word Origin late Middle English: from Jack, familiar form of the given name John. The term was used originally to denote an ordinary man, also a youth (mid 16th cent.), hence the ‘knave’ in cards and ‘male animal’. The word also denoted various devices saving human labour, as though one had a helper (sense (1), and in compounds such as jackhammer and jackknife); the general sense ‘labourer’ arose in the early 18th cent. and survives in lumberjack, steeplejack, etc. Since the mid 16th cent. a notion of ‘smallness’ has arisen, hence senses (4) and (5).Idioms
    all work and no play (makes Jack a dull boy)
     
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    (saying) it is not healthy to spend all your time working; you need to relax too
    (British English, informal) used by or about somebody who is happy with their own life and does not care about other people’s problems a person who can do many different types of work, but who perhaps does not do them very well
See the Oxford Advanced American Dictionary entry: jack