Definition of "jack" []

• Informal A man; a fellow. (noun)
• One who does odd or heavy jobs; a laborer. (noun)
• One who works in a specified manual trade. Often used in combination: a lumberjack; a steeplejack. (noun)
• A sailor; a tar. (noun)
• Games A playing card showing the figure of a servant or soldier and ranking below a queen. Also called knave. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The portions of the operator's talking circuit that are located permanently in the switchboard cabinet are in such cases terminated in a jack, called an operator's _cut-in jack_."
• "Bellinger recommends choosing one topic to focus on -- "the expression 'jack of all trades, master of none' holds true especially in the Web 2.0 world" -- and working on engaging with the top people in that area rather than trying to tackle all the world's problems at once."
• ""You cannot become an expert if one day you work in maternity, the other day you work in the long-term care, and then you are in emergency room," she said, referencing the phrase "jack of all trades, master of none.""