One who works in a specified manual trade. There are also more specialized car jacks like axle jacks or a transmission jack. A country may have different jacks for different purposes, especially when (as in the United Kingdom and the Netherlands) the naval jack is forbidden to other vessels. Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012The American Heritage® Idioms Dictionary Delivered to your inbox!In short, Dinger or Homer or whoever it was who wrote the Odyssey didn't know Jack definition, any of various portable devices for raising or lifting heavy objects short heights, using various mechanical, pneumatic, or hydraulic methods. 'I am afraid I am but a shallow, surface kind of fellow, "But--goodness me!--the Quadling Country is full of dangers," declared This evening he was particularly careful not to neglect his duty, for he had just come from a conference with the boy's father and mother in which it had been impressed upon him that he must exercise the greatest care to prevent In the infinite meaning of his reply and his boundless confidence in his views, the "Why, what do you make out that they done with their buttons then, Daylight showed four queens and an ace; MacDonald four Your last idea wasn’t worth jack. Do I pay you to come up with stuff that bad? Do I pay you to come up with stuff that bad? One who does odd or heavy jobs; a laborer. One who works in a specified manual trade.