—jack /dʒæk/
noun [C] (ALSO knave) (CARD)
► F0 a playing card with a picture of a man on it. It has a lower value than the cards showing a king or queen: » the jack of clubsSee picture: jack of spades (playing card) 
Thesaurus+: ↑Playing cards
noun [C] (BALL)
► F0 a small ball towards which other balls are rolled or thrown in the games of bowls or boulesThesaurus+: ↑Bowls, bowling and croquetnoun [C] (ELECTRICAL)
► F0 a connection between two pieces of electrical equipmentSee picture: (UK) jack plug/(US) plug Thesaurus+: ↑Electrical switches and connections
noun [C] (EQUIPMENT)
► F0 a piece of equipment that can be opened slowly under a heavy object such as a car in order to raise it off the ground: » You need a car jack in order to change a wheel.See picture: jack (for a car) Thesaurus+: ↑Machinery and machines , ↑Household equipment and domestic chores