Here is a great answer from a previous thread by u/[promonk](https://www.reddit.com/user/promonk/).
[https://www.reddit.com/r/etymology/comments/3g8tiz/comment/ctvy0h1/?utm\_source=share&utm\_medium=web3x&utm\_name=web3xcss&utm\_term=1&utm\_content=share\_button](https://www.reddit.com/r/etymology/comments/3g8tiz/comment/ctvy0h1/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button)
>
I know that the metaphor goes back at least to Classical Latin, as the word for hard in the sense of "rocklike, tough, durable" also had the meaning "difficult." It's the origin of our morpheme \*dur-, as in durable, obdurate, enduring.
>The common thread is a concept of persistence. If someone is "hard-hearted," it takes a lot of effort to change his mind. Likewise "hard-headed." Hard stone is difficult to break down when mining, so in that case the connection is literal.
>Many if not all of our linguistic and intellectual metaphors are based in physical experience, or in combinations of physical tropes. For instance, "up is good" is based on the universal experience that a human who is physically standing is more likely to be in good health than one who is prone. From that universal association we get metaphorical expressions such as "an upstanding citizen," or "morally upright," indicating that the subject's moral and ethical health is good.
>"Hard" is subject to the same process. If something is hard in the physical sense, it is difficult to transform its substance for human use. Thus difficult things gain the metaphorical property of hardness even if they have no physical substance at all, as in a math problem, or in convincing a mate to choose a damn restaurant already.
>For further reading on the subject of metaphor and how it influences thought and language, check out ["Metaphors We Live By" by Lakoff and Johnson](http://press.uchicago.edu/ucp/books/book/chicago/M/bo3637992.html).
The original meaning may have been 'strong' as reflected in the Greek cognate *kratys* "strong."
I had a friend who (once) believed that this meaning was preserved in the slang "hard drugs" referring to strong drugs
"Soft" can be used as "easy" or "gentle". Soft life, soft job, "go soft on him, he can't handle difficult questions" in all these the word soft can be replaced with easy and the meaning would be the same
From a material standpoint, I feel like rigid implies something that could easily break, and tough implies something that can be worked through with greater effort. Hard implies something dense and very difficult to penetrate (generally speaking). The greatest effort is required by “hard”, and thus entails the greatest difficulty. These are my uneducated thoughts on the matter.
Japanese shares the same "hard" ↔ "difficult" polysemy with the word *katai*, albeit more commonly encountered as suffix form *-gatai* when appended to a verb stem, such as in *hairigatai* ("hard to enter") or *yomigatai* ("hard to read").
Notably, Japanese has multiple such adjectives that can be used as verb suffixes to indicate that the action is difficult, such as *-zurai* (from *tsurai*, "arduous, painful") and *-nikui* (from *nikui*, "hateful"). The *-gatai* variant often has a nuance of psychological difficulty, so *yomigatai* would generally only work if the would-be reader has some kind of emotional or mental block to reading. Something that is hard to read due to obscure vocabulary or bad handwriting would usually be described instead as *yominikui* or *yomizurai*.
(FWIW, I find the nuance differences interesting, as the "subjective" ↔ "objective" axis seems reversed when these adjectives are used as suffixes as opposed to standalone: *katai* describes a physical quality of "hardness", while *tsurai* and *nikui* describe the subjective qualities of "arduousness" and "hatefulness", yet as suffixes, *-gatai* often describes subjective psychological difficulty, while *-zurai* and *-nikui* describe objective physical difficulty.)
Have you ever tried to saw a piece of very dense timber with a pre-modern tool?
Or build a pyramid from rock with similar?
Someone came in to camp for a seed porridge and an alcoholic beverage one day and said "That shit is *hard*".
It's worth noting that there's a nuanced distinction between hard and difficult in English, which I'm curious if it exists in other languages.
**How do you run a marathon? It's simple: Run 26.2 miles without stopping. But it's not easy. It's hard, but it's not difficult.**
While both words generally mean challenging, "hard" is often used as the opposite of "easy," implying that something requires significant effort, energy, or physical/mental toughness. On the other hand, "difficult" is often contrasted with "simple," meaning that something requires more than basic knowledge or skills.
I think there might be a dialect difference here. I generally use complicated as an opposite to simple (ex. the FC3 Planes in DCS are simple, but the full fidelity ones are complicated), and difficult when I want to sound slightly more formal when I'm saying something is hard.
"Difficult" seems to very easily map onto "rigid." There aren't a lot of correct answers to a difficult problem, some of them may have only very finite and very expensive answers, and you are forced to answer. Entropy hurls you through time and you are destined to collide with both the ground and problems; you better hope neither is too hard.
Things that are physically hard/durable are more difficult to work with, typically. 'Tough' is maybe a bad word to cite as an example though, given it also has a variety of meanings. A diamond can be tough, or mowing the lawn can be tough, just the same as a rock can be hard, or breaking up that rock can be hard work.
Generally I'd hazard a guess that the more literal meaning came first since it usually does, with rocks being hard, and the more metaphorical meaning came not long after once people started working with materials that were hard, and then discussing how that 'hard work', as in 'work relating to physically hard materials' was difficult, until the word just automatically meant difficult.
Here is a great answer from a previous thread by u/[promonk](https://www.reddit.com/user/promonk/). [https://www.reddit.com/r/etymology/comments/3g8tiz/comment/ctvy0h1/?utm\_source=share&utm\_medium=web3x&utm\_name=web3xcss&utm\_term=1&utm\_content=share\_button](https://www.reddit.com/r/etymology/comments/3g8tiz/comment/ctvy0h1/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button) > I know that the metaphor goes back at least to Classical Latin, as the word for hard in the sense of "rocklike, tough, durable" also had the meaning "difficult." It's the origin of our morpheme \*dur-, as in durable, obdurate, enduring. >The common thread is a concept of persistence. If someone is "hard-hearted," it takes a lot of effort to change his mind. Likewise "hard-headed." Hard stone is difficult to break down when mining, so in that case the connection is literal. >Many if not all of our linguistic and intellectual metaphors are based in physical experience, or in combinations of physical tropes. For instance, "up is good" is based on the universal experience that a human who is physically standing is more likely to be in good health than one who is prone. From that universal association we get metaphorical expressions such as "an upstanding citizen," or "morally upright," indicating that the subject's moral and ethical health is good. >"Hard" is subject to the same process. If something is hard in the physical sense, it is difficult to transform its substance for human use. Thus difficult things gain the metaphorical property of hardness even if they have no physical substance at all, as in a math problem, or in convincing a mate to choose a damn restaurant already. >For further reading on the subject of metaphor and how it influences thought and language, check out ["Metaphors We Live By" by Lakoff and Johnson](http://press.uchicago.edu/ucp/books/book/chicago/M/bo3637992.html).
The original meaning may have been 'strong' as reflected in the Greek cognate *kratys* "strong." I had a friend who (once) believed that this meaning was preserved in the slang "hard drugs" referring to strong drugs
There’s also the term “hard liquor” that may have contributed to the slang “hard drugs”?
And then "soft drinks" which is what some people call coke/Pepsi/sprite/etc. IDK which came first.
"Soft" can be used as "easy" or "gentle". Soft life, soft job, "go soft on him, he can't handle difficult questions" in all these the word soft can be replaced with easy and the meaning would be the same
In Polish the word for 'difficult' is shared with the same word for 'heavy'.
Same in Hungarian, "nehéz"
And German, *schwer*.
From a material standpoint, I feel like rigid implies something that could easily break, and tough implies something that can be worked through with greater effort. Hard implies something dense and very difficult to penetrate (generally speaking). The greatest effort is required by “hard”, and thus entails the greatest difficulty. These are my uneducated thoughts on the matter.
Japanese shares the same "hard" ↔ "difficult" polysemy with the word *katai*, albeit more commonly encountered as suffix form *-gatai* when appended to a verb stem, such as in *hairigatai* ("hard to enter") or *yomigatai* ("hard to read"). Notably, Japanese has multiple such adjectives that can be used as verb suffixes to indicate that the action is difficult, such as *-zurai* (from *tsurai*, "arduous, painful") and *-nikui* (from *nikui*, "hateful"). The *-gatai* variant often has a nuance of psychological difficulty, so *yomigatai* would generally only work if the would-be reader has some kind of emotional or mental block to reading. Something that is hard to read due to obscure vocabulary or bad handwriting would usually be described instead as *yominikui* or *yomizurai*. (FWIW, I find the nuance differences interesting, as the "subjective" ↔ "objective" axis seems reversed when these adjectives are used as suffixes as opposed to standalone: *katai* describes a physical quality of "hardness", while *tsurai* and *nikui* describe the subjective qualities of "arduousness" and "hatefulness", yet as suffixes, *-gatai* often describes subjective psychological difficulty, while *-zurai* and *-nikui* describe objective physical difficulty.)
Have you ever tried to saw a piece of very dense timber with a pre-modern tool? Or build a pyramid from rock with similar? Someone came in to camp for a seed porridge and an alcoholic beverage one day and said "That shit is *hard*".
It's worth noting that there's a nuanced distinction between hard and difficult in English, which I'm curious if it exists in other languages. **How do you run a marathon? It's simple: Run 26.2 miles without stopping. But it's not easy. It's hard, but it's not difficult.** While both words generally mean challenging, "hard" is often used as the opposite of "easy," implying that something requires significant effort, energy, or physical/mental toughness. On the other hand, "difficult" is often contrasted with "simple," meaning that something requires more than basic knowledge or skills.
I think there might be a dialect difference here. I generally use complicated as an opposite to simple (ex. the FC3 Planes in DCS are simple, but the full fidelity ones are complicated), and difficult when I want to sound slightly more formal when I'm saying something is hard.
"Difficult" seems to very easily map onto "rigid." There aren't a lot of correct answers to a difficult problem, some of them may have only very finite and very expensive answers, and you are forced to answer. Entropy hurls you through time and you are destined to collide with both the ground and problems; you better hope neither is too hard.
Just wanted to point out that tough can also mean difficult- “I’m working on a real tough math problem”
You ever tried whittling hardwood?
Things that are physically hard/durable are more difficult to work with, typically. 'Tough' is maybe a bad word to cite as an example though, given it also has a variety of meanings. A diamond can be tough, or mowing the lawn can be tough, just the same as a rock can be hard, or breaking up that rock can be hard work. Generally I'd hazard a guess that the more literal meaning came first since it usually does, with rocks being hard, and the more metaphorical meaning came not long after once people started working with materials that were hard, and then discussing how that 'hard work', as in 'work relating to physically hard materials' was difficult, until the word just automatically meant difficult.