There are 4 main definitions of jack in English:


Line breaks: jack
Pronunciation: /dʒak


1A device for lifting heavy objects, especially one for raising the axle of a motor vehicle off the ground so that a wheel can be changed or the underside inspected.
More example sentences
  • Finally, lower the jack so the wheel is back down on the road.
  • The object of this invention is to provide a light, simple and convenient jack by which to raise the wheels of automobiles, when not in use, so as to relieve the tires from the pressure due to the weight of the machine.
  • With the suspension set to high, the jack needs only to lift the car fractionally to allow the wheel to be swapped.
2A playing card bearing a representation of a soldier, page, or knave, normally ranking next below a queen.
More example sentences
  • Notice also that it is not legal for East to put the jacks in the front hand, because it would then not be possible to make a middle hand that was better and a back hand that was better still from the remaining ten cards.
  • Police in Xinyang, a city in Henan province, have produced a half million packs of cards with the pictures of ‘notorious suspects’ on aces, kings, queens and jacks in an effort to capture the criminals.
  • If the turn-up is a Jack, dealer scores one white chip at once; if the turn-up is the Joker, dealer scores one blue chip at once and the cards are immediately thrown in.
3 (also jack socket) A socket with two or more pairs of terminals designed to receive a jack plug.
More example sentences
  • The right side is home to an earphone jack, power socket and, under a cover, a USB 2.0 port.
  • They weigh 14 ounces and are powered by four AA batteries, with input capabilities for a radio or scanner, and an output jack for receiving or recording.
  • An earphone jack includes an insulative housing and conductive first, second and third contact members.
4A small white ball in bowls, at which the players aim.
More example sentences
  • Lawn bowling required four bowls for each player and a jack for a goal.
  • Two teams get four balls each and aim to get them nearest the white ball or the jack.
  • The only way to develop the skill of accurately estimating the distance from the bowl to the jack is to practise doing it and keep on until you gain consistency to within a few centimetres.
5 (jacks) A game played by tossing and catching small round pebbles or star-shaped pieces of metal or plastic.
More example sentences
  • In Korea, young girls play a game of jacks, tossing small stones onto the ground, throwing a ball up in the air, and and trying to pick the stones up before catching the ball.
  • Tharp compares the work to a game of jacks, one in which you pick up an increasing number of pieces with one hand while bouncing a ball in the other.
  • The product that animates Harris's work life is Crazy Bones - packs of small, brightly hued plastic figurines that are used to play a variety of games similar to jacks or marbles or dice.
5.1 (also jackstone) A pebble or piece of metal or plastic used in the game of jacks.
6 (Jack) informal Used to typify an ordinary man: he had that world-weary look of the working Jack who’d seen everything
More example sentences
  • Suddenly, a Jack, another type of fighter, got behind.
  • She was only 15, so she was not having an affair with a Jack.
  • There may or may not have been a Jack rummaging around in it.
6.1chiefly US informal Used as a form of address to a man whose name is not known.
6.2North American informal A lumberjack.
6.4 archaic A steeplejack.
6.5The figure of a man striking the bell on a clock.
7A small version of a national flag flown at the bow of a vessel in harbour to indicate its nationality.
More example sentences
  • At daylight we hoisted the jack for a pilot and a Delaware pilot came off, Boat C, but couldn't take us to New York.
  • At daybreak they attempted to rouse attention on land; they hoisted the jack for a pilot and at 7 a.m. sent up signals of distress and fired a gun.
8 [mass noun] North American informal dated Money.
9A device for turning a spit.
More example sentences
  • When running a spit from a weight driven clockwork jack, it is essential to ensure that the joint or bird is properly centred, or the spit may stop running.
10A part of the mechanism in a spinet or harpsichord that connects a key to its corresponding string and causes the string to be plucked when the key is pressed down.
More example sentences
  • Volume can be increased only by engaging more sets of strings and jacks.
  • The jack sits just under the bottom row on the keyboard, and in a pretty visible location.
  • The harpsichord's jack-and-plectrum action plucks the strings instead of striking them, creating a sharp, bright tone and a "snappy" keyboard feel.
11A marine fish that is typically laterally compressed with a row of large spiky scales along each side, important in many places as food or game fish. Also called pompano, scad.
[originally a West Indian term]
More example sentences
  • On any dive one can easily spot angel fish, manta rays, hammerhead sharks, jacks and trevailles, barracudas… Finding Nemo would be impossible if he got lost here.
  • Located at the southern tip of Pulau Pinang, this area swamps with currents, and hence presents a good chance to observe sharks, barracudas, jacks and schools of yellowtail.
  • Even the fish appeared to be experiencing difficulties swimming against the current; and the site was abuzz in action, as jacks, snappers and groupers busily swarmed about.
12The male of various animals, especially a merlin or (US) an ass.
More example sentences
  • A mule results from a cross between a female horse, or mare, and a male donkey, or jack.
  • The young female kestrel may have paired off with a young male. We spotted them chasing off a Jack Merlin.
13Used in names of animals that are smaller than similar kinds, e.g. jack snipe.
More example sentences
  • The Jack Snipe is an extremely difficult bird to see, partly because they are not very common but mostly because they are so well-camouflaged they will often sit unnoticed and let you walk past them.
  • In the spring male Jack Snipes court females in an unusual way. The male will fly several hundred feet in the air and perform a dive. While in the air he will also create a humming noise by fanning his tail.
14US informal short for jack shit.
More example sentences
  • We all know that neither candidate will do jack squat anyway.
  • I don't know jack about university finances, of course, but I have yet to hear of any school going broke over unionizing.
  • Civics isn't even taught anymore and nobody knows jack about history.


late Middle English: from Jack, pet form of the given name John. The term was used originally to denote an ordinary man (sense 6), also a youth (mid 16th century), 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, sense 3, sense 9, sense 10, and in compounds such as jackhammer and jackknife); the general sense 'labourer' arose in the early 18th century and survives in cheapjack, lumberjack, steeplejack, etc. Since the mid 16th century a notion of 'smallness' has arisen, hence sense 4, sense 5, sense 7, sense 13.


before one can say Jack Robinson

informal Very quickly or suddenly.
More example sentences
  • A friend of mine in Brixton kept koi carp in a raised toilet and this heron came straight in and ate the fish before you could say Jack Robinson.
  • Yet, with a ton of people assigned to wait on customers - eight clerks were politely servicing people - I had my onion bagel with vegetable tofu spread and a juice before one could say Jack Robinson.
  • The canoe slides into the water in the blink of an eye and before you can say Jack Robinson it's twenty yards off shore.

every man jack

informal Each and every person (used for emphasis): they’re spies, every man jack of them
More example sentences
  • Those who had short-changed or betrayed him were no longer on the scene in Europe or America - every man jack of them had passed on, he was pleased to note.
  • In the second half at Bolton in particular, every man jack in that Rovers team gave every ounce of effort to preserve that lead in the face of a continual aerial bombardment.
  • As we went up the climb, we passed every man jack of 'em, all of them straining heroically.

I'm all right, Jack

informal Used to express selfish complacency.
More example sentences
  • That sounds like: ‘I'm all right, Jack, shame about you.’
  • Conservative voters may therefore assume it is sensible for them to support a party that will improve their already (generally) privileged economic situation through apparent tax reductions, while dismantling the components of the welfare state that are most needed by others. Such "I'm all right, Jack" thinking is shortsighted.
  • I hope he is not saying "I'm all right Jack (because I'm super rich), why aren't you?". Because most South Africans are not all right, many are panicking.

jack of all trades (and master of none)

A person who can do many different types of work but who is not necessarily very competent at any of them.
More example sentences
  • We are always conscious of the fact that a company that sells itself to several different industry sectors, can be seen as a jack of all trades and a master of none.
  • Competitors will have to be a sort of jack of all trades when it comes to entertainment as they will be expected to perform all types of acts as diverse as from singing a song to changing nappies.
  • You are trying so many different things that you have become a jack of all trades and a master of none.

on one's jack (or Jack Jones)

British rhyming slang On one’s own.
More example sentences
  • Two weeks later, it's a chilly October night, I'm on my Jack Jones and the ‘phone rings.
  • The last time was 2002, when I played the Pyramid Stage on my jack jones, which was the most terrifying moment I've ever had on stage.

Phrasal verbs

jack someone around

North American informal Cause someone inconvenience or problems, especially by acting unfairly or indecisively.
More example sentences
  • They will jack you around, make wild promises and then when it's too late you stand to lose your home.
  • So I guess he wants to jack me around for 6 months and then expect me to pay another $1800?
  • The shop was going to jack me around on the time to put the engine back in.

jack in (or into)

informal Log into or connect up (a computer or electronic device).
More example sentences
  • Given that Neo had spent his entire life inside The Matrix - more accurately, inside a pod of goo while jacked into a massive computer - how could his ear be pierced?
  • She was able to jack into the computer's mind and learn what it knew.
  • Bandwidth is often seen as a public resource, and people who would blanch at the thought of breaking into a computer room wouldn't think twice about jacking into wireless networks.

jack something in

British informal Give up or stop doing something, especially a job.
More example sentences
  • It got so depressing I thought of jacking the whole thing in.
  • It's like a relationship: how long do you keep working at the problems before jacking it in.
  • There was everything to play for - so why is he jacking it in even as Donald returns from his sick bed?
give up, stop, cease, discontinue, desist from, swear off, forbear from, abstain from, cut out, renounce, forswear, forgo, abandon, have done with;
resign from, stand down from
informal quit, kick, leave off, knock off, pack in, lay off, chuck, ditch

jack off

vulgar slang Masturbate.

jack up

1Inject oneself with an illegal drug.
More example sentences
  • Eric was just tired and still a little jacked up on drugs, then they did some therapy and he got even more tired.
  • He was still pretty much jacked up on drugs, and the rest of the team had practically left.
  • And how else are you going stop a 350 pound guy, all jacked up on drugs?
2Australian Give up or refuse to participate in something.
More example sentences
  • And it's the same with ADHD, there's a continuum of this behaviour and it gets to a point where either the parents, the teachers jack up or doctors say here's the behaviour beyond which we would say this is a disease.

jack something up

1Raise something, especially a vehicle, with a jack.
More example sentences
  • The officer then got the jack from the boot of the vehicle, jacked it up and released Phillips.
  • He goes to Mark's side of the car and asks him to step out of the vehicle so he can jack it up.
  • Next time you take your car to a Greek or Italian mechanic and he uses the Force to jack your car up instead of the hoist, be very afraid.
1.1 informal Increase something by a considerable amount: France jacked up its key bank interest rate
More example sentences
  • Virtually all restrictions on fruit machines will be removed and the amounts to be won will be jacked up to £1 million.
  • It's a little disconcerting hearing the wide-eyed troubadour so distraught, but if it's any consolation, the emotional intensity of his folksy confessionals and heartfelt power-pop nuggets have been jacked up considerably.
  • And I think they have enough new products to at least hold on to domestic market share without needing to jack them up any further.
increase, raise, put up, push up, up, mark up, make higher, boost, step up, lift, augment, inflate, escalate
informal hike (up), bump up
2NZ informal Arrange or organize something: they did a national service in jacking this racing up
More example sentences
  • I will PM you with my details and maybe we could jack something up.
  • Perhaps we could jack something up with the projector - just low key for those that want to talk about something.
  • Herb had jacked up a whole cinema for a fairly-near-to-opening screening of The Lord of the Rings: The Return of the King, so we went along for a look-see…

Definition of jack in:

There are 4 main definitions of jack in English:


Line breaks: jack
Pronunciation: /dʒak


[with object] North American informal
1Take (something) illicitly; steal: what’s wrong is to jack somebody’s lyrics and not acknowledge the fact
More example sentences
  • They make the Evening News: they filmed a local gemstone store robbery in progress, a crime in which $10 million in jewels was jacked.
  • I was far from my normal spot next to the window, but didn't partially mind the getaway from Marie who always tried to jack my seat.
  • De Niro's performance communicates his longing for normalcy so well that the movie doesn't need Bassett as the moral balance who tells him to quit jacking diamonds.
1.1Rob (someone): they told police they’d been prowling the streets looking to jack someone
More example sentences
  • I hid it inside my sweatshirt so if someone tried to jack me.
  • I mean you just jacked someone else's car. You cheat, steal, and bend the rules to your liking whenever you want.
  • Soon they're swigging beer, blowing joints, ripping off drug-dealers and trying to sell a gun they jacked from a local gang.


1990s: from hijack.

Definition of jack in:

There are 4 main definitions of jack in English:


Line breaks: jack
Pronunciation: /dʒak


[predicative] Australian informal
Tired of or bored with someone or something: people are getting jack of strikes
More example sentences
  • You know it's getting bad when Thomas Friedman, the NY Times' epitome of patience, is getting jack tired of France;


late 19th century: from jack up 'give up'.

Definition of jack in: