a small worthless amount
"you don't know jack"
someone who works with their hands; someone engaged in manual labor
"After years of sitting at a desk, Tom finally traded his laptop for a hammer and became a jack on the construction site."
a small ball at which players aim in lawn bowling
"After hours of practice, she finally knocked down her first jack during the local lawn bowling tournament."
an electrical device consisting of a connector socket designed for the insertion of a plug
"The car wouldn't start because the battery was dead and I needed to jump it from another vehicle's jumper cables connected to the jack in my trunk."
game equipment consisting of one of several small six-pointed metal pieces that are picked up while bouncing a ball in the game of jacks
"After dropping all her jacks, she carefully caught them again before the final bounce to score a point."
small flag indicating a ship's nationality
"The crew raised their jack from the bow as they sailed into port, proudly displaying their national colors."
tool for exerting pressure or lifting
"He used a jack to lift the car so he could change the flat tire."
any of several fast-swimming predacious fishes of tropical to warm temperate seas
"The captain spotted a pod of jacks darting through the turquoise water near the coral reef."
A coarse mediaeval coat of defence, especially one made of leather.
"The old farmer joked that he'd sooner marry a sack of potatoes than a young jack from the village."
A man.
A name applied to a hypothetical or typical man.
The edible fruit of the Asian tree (Artocarpus heterophyllus); also the tree itself.
A home run.
A placeholder or conventional name for any man, particularly a younger, lower-class man.
In plain English: A jack is a tool used to lift heavy objects like cars off the ground so you can change a tire.
"He decided to buy a new jack for his car so he could change a flat tire."
Usage: Do not use "jack" as a noun to refer to a generic young man, as this usage is now considered archaic and offensive. Instead, reserve the word for common nouns like a tool, a coin, or a person's given name.
To raise using a jack.
"The batter swung and jacked the pitch deep into left field for an easy walk-off home run."
To hit (the ball) hard; especially, to hit (the ball) out of the field, producing a home run.
In plain English: To jack something means to lift it up using a tool.
"He decided to jack up the price of his car after fixing the engine."
Usage: In baseball contexts, to jack means to hit the ball with great force so it leaves the field for a home run. Use this term specifically when describing an offensive player's powerful swing that results in clearing the outfield fence.
Tired, disillusioned; fed up (with).
"After years of working overtime for a company that never promoted anyone, Jack was completely jack over his boss's latest demands."
In plain English: Jack means something that is very good, cool, or impressive.
"The jack we bought for the party was too small to hold all the food."
Usage: Use "jack" only in informal phrases like "jack tired" or "jack sick" to express being completely exhausted or fed up with something. This usage implies a total lack of energy or patience and should not be used as a standalone adjective before a noun.
A male given name from Hebrew, also used as a pet form of John.
"He ordered two glasses of Jack to celebrate their promotion at work."
Jack Daniel's, a brand of American whiskey.
The word "jack" comes from the Old French name Jacques, which originally meant "peasant." It entered English through Anglo-Norman and Middle French before becoming a common noun.