The qestions about "not"

Question

In recent days,I found myself not knowing the word"not" at all,and this really makes many misunderstanding for me. Therefore, there are two questions about "not".

Emma:You must be happy that you didn't fail your important exam yesterday.

Anna: Absolutely……not. The fact is that I'm "very happy" not just "happy".

One of the most common definition of "not" in my dictionary is "used in order to make a word or expression have tge opposite meaning".

Thus,one question is "Can I use the word "not" like the sentence Anna says?". In other words, can I use the word "not" to emphasize the difference of the degree rather than the opposite meaning?

The another is ,Why does "not a bit" mean "little" and "not a little" mean "much"? Are they idioms?

After all,"a little" and "a bit" are the similar phrase to mean "some".

Answer 1

In your first example, not is being used to indicate the falsehood of a simple statement:

No, I'm not happy. I'm very happy.

Or, in a similar context:

"No, I don't like it. I love it.

Such negations are commonly made in order to make a point. They don't need to actually indicate an opposite.

It's the same thing as saying not exactly.

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Also, not a bit and not a little do mean the same thing.

Based on context, both can mean none at all or a lot.

Consider:

Q: "Do you like it?"
A1: "Not even a bit."
A2: "Not even a little."

In both answers, the words indicate that you don't like it at all—that there is nothing about it you like.

Or:

Q1: "You must be a bit happy."
A1: "Not just a bit, a lot.

Q2: "You must be a little happy."
A2: "Not just a little, a lot."

In both of these conversations, the words are expressing the opposite of a small amount—that you are a great deal happy.

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Of course, the two words are often used in combination for emphasis.

But, again, context determines if they indicate nothing or a lot:

Not even a little bit.

This means nothing.

No just a little bit.

This means a lot.