The word “Jack”

If it helps you, etymonline.com says: “jack(n.) late 14c., jakke "a mechanical device," from the masc. name Jack. The proper name was used in Middle English for "any common fellow," and thereafter extended to various appliances which do the work of common servants (1570s). Also used generically of male animals (1620s, see jackass, jackdaw, etc.).” Basically, ‘Jack’ was once such a common name that you could say ‘jack’ to mean “any generic guy”, “some random dude”, etcetera; which explains “lumberjack” and “jack-of-all-trades”, at least. (He’s one of those lumber-worker Jacks, you know? Like if I referred to “one of those software-dev Nicks” at my job. One of the software devs who is named Nick, there’s a million of them) And then people just kept extending the meaning to include more and more random items, I guess. 

As others have said, "Jack" is very nearly the most generic male name. The equivalent female name is usually said to be "Kate". There are lots of variants, of course, but if you look at stories, plays, movies, TV shows, and novels--going back several hundred years--it's stunning how often some "Jack" hero is paired with some "Kate" heroine.

"Jack" was originally a pet version of the name "John" (from the french Jacques) and eventually sort of morphed into a slang term for an ordinary man (sort of like "guy" today). So you'll see it come up in all sorts of strange places. "Jack of all trades" literally just means "a man of all trades," "jackknife" is "a regular person's / all purpose knife," and so on. "Jackass" is just "a guy (male) ass (donkey)." the mechanical jack that you'd use to lift your car also comes from there, but for some reason I'm having trouble finding a precise etymology. And that mechanical jack is where "jackhammer," "jack up," and so on come from.

Potentially not the answer you're looking for, but Jack is also Aussie military lingo. "Jack" meaning someone whom is selfish and does things for themselves. Common phrase used "never go Jack on your mates". Naturally, used in non-military contexts but is very common in the military.

as for Jackknife and Jack of all trades, I believe it's just because someone named Jack did something cool

As a verb, it means to ratchet or raise something using a pneumatic device (the device is also called a jack). It also used to be an informal word for a man, sort of like "guy." I would imagine that's where a lot of these uses come from.

Remember: there's a big difference between **helping your uncle Jack off a horse** and **helping your uncle jack off a horse**.

Jack is an antiquated word for a guy, which gets turned into a helper, a tool that helps you, the action done with a tool that helps you, the card that represents the normal guys, a male version of something. Most of the uses you listed come from one of those, with the exception of jack knife which is a mystery.

Wow, Oxford gives FIFTEEN definitions. deriving originally from middle english given name John, nickname Jack, and then it got adopted for so many things.

Interesting question that sent me down a rabbit hole of research. It seems like it usually it means a commoner, or male animal. It's also a hydraulic device. Lumberjack- A commoner that works with lumber. Jackpot- Has to do with the face card "jack" in a set of playing cards, which in turn comes from the meaning of commoner. Jack-hammer- Works with hydraulics. Jackass- A male donkey. Jack-o-lantern- Comes from an Irish folktale where the main character was named Jack. Jack in, up, and off- Probably refers to the use of a hydraulic device to lift things.

Jack is a man's name, a nickname for John. Over the centuries, it's acquired and lost many slang meanings, and left behind a ton of words and idioms related to those. from Google's dictionary function: >late Middle English: from Jack, pet form of the given name John . The term was used originally to denote an ordinary man (jack1 (sense 7)), also a youth (mid 16th century), hence the ‘knave’ in cards and ‘male animal’. The word also denoted various devices saving human labor, as though one had a helper (jack1 (sense 1, sense 3, sense 10, sense 11), and in compounds such as jackhammer and jackknife); the general sense ‘laborer’ 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 jack1 (sense 5, sense 6, sense 8, sense 14).

"Jack" is a nickname for the name, "John." In English, John is a ubiquitous name. When we find a person with no ID, they're called a "John Doe." A prostitute's customer is called a "John." "Jack" is often used in a similar way to denote an everyman.

Even the experts are confused on this subject at times. Many word origins are centuries old and the original usages are lost to time. When it comes to jackknife, [Etymonline has only speculation of its origins,](https://www.etymonline.com/search?q=jackknife) suggesting the word might be American and might have referred to the knives favored by sailors. Etymonline does note that using "jackknife" to describe a tractor-trailer\* accident accident dates back to 1966, as the two sections fold together in a manner resembling a folded jackknife. \* Other words for tractor-trailer include semi-truck, semi, and 18 wheeler

So OP... what you're saying is, you don't know jack shit? /sorry

Etymology of Jack was to denote an ordinary man. Later a term to denote a young man (the jack in cards, below a queen) and later a term for a laborer (lumberjack) and then something to denote something that HELPED in labor (jackhammer, jackknife) then something to denote smallness (a lot of small fish, specifically the males of the species are called jack). I also think that's where jackshit came in. As for jerk off/jack off for masturbation, first came the motion (jerk), then jack which was another term for penis (I assume for small thing)

It's a name now, but back in the middle ages, it meant "man" or "guy." Hence all the words & phrases like lumberjack(guy who harvests lumber) and jack of all trades(man of many skills)

Jack is a good example of how English can be a tonal language. "I helped my Uncle Jack off a horse" (rising tone) "I helped my uncle jack off a horse" (falling tone) Those sentences have different meanings.

“One of my nemeses”, if we’re being pedantic.

“Jack” is a tricky word because it has many unrelated meanings. It started as a name but now appears in tools (car jack), phrases (jack up), and compound words (jackpot, jackknife). It doesn’t have one meaning—context is everything!

Bill Bryson in his book on the English language looked into it. He decided we just really like the name Jack.

It comes from the name Jack, which in turn comes from the French Jacques which in the Middle Ages became a synonym for commoner or peasant, probably why it is used in words and phrases concerning the working class or their tools. The word jacquerie means a rising up of the commoners.

Jack can mean the devil - e.g. Jack-in-the-box (a toy), Jack-in-the-hedge (a spicy plant), Jack Frost.

Jack was used as a noun to describe a helper, the original Jack ( in the playing cards) helped the knights put on their armour., like a page or knave. This was given to other trades or apprentices Steeplejack Lumberjack Cheapjack. Because these apprentices were small boys originally, jack came to used for small ones And as a jack would be the one going up and down Jack came to mean this A car jack Jackhammer Small Jackknife The jack in bowls Jackdaw Jackrabbit Every man Jack As jack was in cards we get jackpot As a jack was small Jack shit And as a knave was also a dodgy geezer Jack meant steal Hijack Jack something ( steal/ rob) Nd that was in turn used as a frustration I am jacked by all this And then the rude definition Jack off Was perhaps a small thing going up and down to help frustration Jack was an ensrogn flag, the Union Jack being an example Jacquard comes from this and jacquaries were revolutionary people. So a hot h pot h of languages as already said

Many English phrases, especially older ones from England, use names to indicate something. Name can indicate the gender of an animal. Jack rabbit, jack ass (ass is a donkey), tom cat, Billy goat. These all indicate the animal is male. Name can just stand in for a person. Jack of all trades: a person who does any job. Average Joe: an average person. Johnny come lately: someone who is new to the community. Jack is a playing card, ranked above 10, below Queen. Jackpot probably comes from a particular gambling card game. Jack is also a tool that lifts something. Some meanings are related to that.

The word jack means “small”. A jack knife is a small knife, a jack staff is a small flag pole on a ship, a jack pine is a small pine (compared to red pine or white pine). A lumberjack is a small person who works in the woods, eventually it names anyone who works in the woods.

Jack use to be just a word for guy/dude so you have King, Queen, there use to be another royal position but the commoners just called it the Jack

It's just a fairly average man's name. It's essentially used as "normal person." Lumberjack -> person that produces lumber Jackpot is from the playing card "Jack." Jack of all trades -> fairly middling/average skill level at a variety of skills I'm not sure what's up with jack-knife Jack-hammer is from a different meaning of "jack" as in a raising and lowering motion. It's pretty unusual for it to be used that way now, but that's also why the machine that lifts a car is called a "jack." Jackass -> originally a male donkey, "Jack" is a male name

I have always seen this as "Craftsman" but I never had any linguistic prove for this.

as far as i know it's just a slang word w no meaning

Interesting question. I'm a native speaker and have never thought about it.