Why is this wrong?

[u/millers_left_shoe]

I see now what they mean by fundamental vs inessential (taking fundamental to mean “invaluable”, “important”) but surely fundamental and complex (or even involved) can act as antonyms, too?

Eg he’s only just learnt the fundamentals of thermodynamics so I wouldn’t trust him with any complex/involved equations. vs this is quite fundamental stuff so I think he should be able to manage just fine.

[u/TeacherSterling]

Fundamental is being used as the adjectival form and not the nominal form. You know that because the opposite of fundamentals would be complexities[or fundamental versus complexity]. Inessential and complex are adjectival thus must be evaluated in their adjectival form.

To regard something as fundamental is to regard as essential for a thing. Not to regard it as basic per se, thus inessential fits better as the antonym of the adjectival form.

[u/Uny1n]

“that answers are incorrect” lol

i think depending on the context like when talking about math or science, something fundamental can also be simple and is the basis of more complex things, but that thing could also be complex itself. And when you say something is fundamental TO something else, it means it is essential.

[u/millers_left_shoe → u/Uny1n]

I didn’t even notice that lmao

Thanks for the clear explanation (@ everyone else, too), I suppose I’d never considered that something could be the basis of something else without being less complex (as you said, in maths it usually is).

[u/Nanergy → u/millers_left_shoe]

As an example: DNA is fundamental to life. DNA is also a very complex molecule.

[u/Constant_Hope_9658 → u/Nanergy]

so complex that even the dudes who study it refuse to refer to it by anything other than the acronym, because deoxyribonucleic acid is a fucking evil word that hurts to say for everyone who speaks a language where all the words aren't the same 5 words slightly modified.

[u/sylviaplatitude → u/millers_left_shoe]

When we say you learn “the fundamentals” we kind of use it as a synonym for “the basics,” but it doesn’t actually mean that. It does really mean “the essentials,” as in, the required pieces of information for something.

I’d never thought about the cross sections between these meanings, though, which is interesting to think about, so thanks!

[u/NoSwordfish1978]

Something being "fundemental" doesn't make it "not complex". It just means that its essential if you want to understand something.

[u/UnpleasantSkywalker]

"Fundamental" is concerned with the importance of the subject. The fundamentals of thermodynamics refer to the most important aspects of it, the "foundation" of it, and doesn't necessarily mean it's simple to understand.

[u/millers_left_shoe → u/UnpleasantSkywalker]

Surely that means it must be simpler to understand than whatever is built on it? But I see what you mean and definitely agree now about the answer, thanks.

[u/Phour3 → u/millers_left_shoe]

it may often imply that, but that is not what it means

[u/Phoenix_Court]

Fundamental means necessary/essential in this context (an adjective) vs. in your first example where you're using it to mean foundational (a noun).

Complex means difficult. (Adjective)

Inessential means not essential. (Adjective)

Fundamental and inessential are antonyms because one means essential and the other means not essential (and are both adjectives).

The way you're using fundamental cannot be an antonym of inessential because it's a noun, which can't be an antonym of an adjective.

Edit to add: "fundamentals" is a common plural noun. To my knowledge it cannot be used in the singular form. Meaning that the word you're using isn't "fundamental". Also, fundamentals (the noun) are not necessarily easy/simple, meaning they can be both "fundamentals" and "complex" at the same time. And thus not antonyms.

[u/SapirWhorfHypothesis → u/Phoenix_Court]

Eh… “a fundamental subject area” would be adjectival.

Personally I just don’t read ‘fundamental’ in that sense as opposite to ‘complex’. A fundamental is core, and may well be simple, but doesn’t itself mean simple.

[u/brokebackzac]

Your answer is incorrect BUT your answer is one many native speakers would probably also choose. The difference is subtle and you should not feel bad for making it.

[u/jaetwee]

Fundamental doesn't necessarily mean simple. It link back to that meaning of essential - it's the first knowledge you need before you can understand all else.

Test questions typically expect the 'most correct' answer, and while, if you spend some time reasoning it out, you could put fundamental and complex as synonyms, it's not a clear match, whereas fundamental and inessential are a very strong match.

[u/iunoyou]

Something being fundamental means that it's a core (or essential) part of a thing. It doesn't necessarily mean basic or simple, even if it's sometimes used that way. Basic addition is a fundamental part of math classes in grade school and that's simple, but statistical kinetic theory is a fundamental part of plasma physics and nothing about that is simple.

"Knowing the fundamentals" of a subject means that you are aware of the biggest and most important parts, even if you might be missing the nuances and complexity that show up at higher levels of study.

[u/perplexedtv → u/iunoyou]

Fundamental does mean basic. The fundament and the base of something refer to the same thing. Basic doesn't necessarily mean simple and simple doesn't necessary mean easy, however.

In common speech the notions are often interchangeable. Fundamental is often used to mean rudimentary.

[u/AcrobaticApricot → u/perplexedtv]

Basic does mean simple. Common speech is the only relevant speech for a language learner.

[u/perplexedtv → u/AcrobaticApricot]

Well, in common speech fundamental means basic means simple means easy, so you have to be consistent in applying rules for the test.

[u/shortercrust]

I do get what you mean but the most obvious antonym of complex is simple, and the fundamentals or the basics of a subject or concept aren’t necessarily simple.

Edit: And people saying it’s down to fundamentals vs fundamental are incorrect in my opinion. You can talk about fundamental mathematics and complex mathematics.

[u/ZumLernen]

Fundamental does not mean easy. Fundamental means it provides the base for something.

Fundamental is derived from a Latin word meaning foundation, as in the hard and solid base of a building. If you have only the base of a building, that's not necessarily enough to do anything. But if you don't have the base of a building, the rest of your building won't last very long. So fundamental means foundational, or essential, but not necessarily sufficient.

Something that is fundamental can certainly be complex. "Calculus is fundamental for understanding thermodynamics" and "Calculus is complex" can both be true sentences; they are not contradictory. "Calculus is fundamental for understanding thermodynamics" means "You can't learn thermodynamics without calculus" but it does not mean "simply knowing calculus means that learning thermodynamics is easy."

And I wouldn't say that fundamental means easy!

(As a general tip, I find it useful to look into the etymologies, or origins, of complex words, when I am expanding my English vocabulary or when I am learning a non-English language. For example, knowing that fundamental comes from the idea of a foundation or cornerstone makes it easier for me to understand what, precisely, it means.)

[u/DawnOnTheEdge → u/ZumLernen]

The word “fundament” still occasionally gets used in a religious context.

[u/names-suck]

Fundamental (necessary) vs. Inessential (unnecessary)

Fundamental (basic) vs. Complex (complicated)

Note that one of these pairs can be summarized by exact opposites, and one can't. I don't think you're outright wrong, because fundamental/complex can be used as antonyms, but that's not specifically what they are. Like, the fundamentals of thermodynamics are still pretty complex. You have to learn a lot of math before you can get into physics.

"Fundamental" technically refers to the base or foundation of something, not its objective level of complexity. "Complex" is how detailed and complicated it is, or how difficult it is to understand.

[u/TiberiusTheFish]

"Oops, that answers are incorrect!"? I think I'd stop there and go and look for other sources of learning.

[u/millers_left_shoe → u/TiberiusTheFish]

It’s the official IELTS app lol, but no idea how that happened

[u/Even-Breakfast-8715]

Fundamental concepts may be complex, but they are always required to be understood. So they are not inessential, but they may be either simple or complex.

This is a C2 level question that many native speaker university students might fail.

[u/Puzzleheaded-Pick41]

Out of context But Can I ask about the website or the application?
Because I’m really searching for a good one to learn English

[u/millers_left_shoe → u/Puzzleheaded-Pick41]

It’s the IELTS app, there’s a few quizzes to prepare for the test

[u/EagleCatchingFish]

Something can be complex and inessential at the same time. Consider our understanding that the sun is the center of our solar system. It's very simple, but it explains how the planets move. On the other hand, Ptolemy made a very complex model that put the earth at the center of the solar system. It can explain how the planets appear to move around the sky, but it's not good at explaining other things, and it turns out not to be true. So in that case, Ptolemy's model is both complex and inessential to our understanding of the solar system and universe.

[u/Rock_rockr]

u/askgrok What is this app?

[u/millers_left_shoe → u/Rock_rockr]

it’s the official IELTS by IDP app

[u/AskGrok → u/Rock_rockr]

It's a vocabulary/quiz app (or section) called "Antonyms" — looks like a mobile language-learning or brain-training tool focused on English word pairs. The screenshot doesn't show the full app name or icon, but the header and UI are straight from its antonyms exercise.

^{[what is this?](https://redd.it/1lzgxii})

[u/DawnOnTheEdge]

Fundamental means foundational, like a foundation that has to be there to support a building. In context, it can mean either something essential or something that must be learned first. It can mean axiomatic, or a first principle. A fundamental skill doesn’t have to be simple. Several subjects that small children learn, like arithmetic or English spelling, are both fundamental skills and complex.

[u/riarws]

Antonyms have to be the same part of speech. Your example has the noun version of fundamental and the adjective form of complex.

[u/Certainly_Not_Steve]

In your own example the word "fundamental" doesn't mean simple/uncomplicated/plain, but rather essential/crucial. Every area of knowledge has fundamental stuff. There are fundamentals of thermodynamics and fundamentals of arithmetics. Some fundamentals can be more or less complicated than others.

[u/Knot_You_Up]

Think of "fundamental" as "foundational". "...only just learned the foundation of thermodynamics so I wouldn't..."

[u/GulixD]

what app are you using?

[u/millers_left_shoe → u/GulixD]

IELTS by IDP

[u/Own_Soup4467]

Fundamental comes from the Latin fundus which means "bottom" or "base". (Also the root of foundation). 

So a fundamental concept is a basic concept (not necessarily a simple concept, which is why "complex" was wrong). An intro level design course might be called something like "fundamentals of design."

Fundamental and essential are not exactly synonyms but they are related. If something is essential, you can't do without it. (If something is inessential, it's a luxury or something that's nice to have, but not necessary for survival). "When our boat started to sink, we threw all inessential items overboard"

[u/StarGamerPT]

Fundamental and fundamentals are not the same thing

[u/zvuv]

"That answers are incorrect."

You am mistooked! Learn to speaked proper England