大きい vs 大きな

One sentence is grammatically wrong. Which one is it?

1. ジョンさんの 心こころの 友達ともだちは 大おおきい。
2. ジョンさんの 心こころの 友達ともだちは 大おおきだ。
3. ジョンさんには 大おおきい 心こころの 友達ともだちが いる。
4. ジョンさんには 大おおきな 心こころの 友達ともだちが いる。

大おおきい and 大おおきな both mean “big.” There is no clear difference in meaning. So if you have just started to study Japanese, the only thing you need to remember is that 大おおきな is NOT a なadjective and it has to have a noun afterwards – i.e. you cannot use it at the end of a sentence like the above b. This is because 大おおきな is classified as 連体詞れんたいし, which is translated as “a prenoun adjectival” or “a noun adjunct” (it’s not important to remember these grammar jargon but you need to know the difference in function/usage) and that means it can only be used in front of a noun.

So the answer to the above question is 2. You cannot replace な of 大おおきな with だ to end a sentence.

If you are studying for the JLPT N5 exam, stop reading here.

Question to an advanced learner

If you are an advanced learner, I have another question for you: are the images of John’s friend described in the other 3 sentences (1, 3 and 4) the same?

I said there is no clear difference in meaning but it does not mean that there is no difference. Native speakers do choose one over the other depending on the context, so I will try to explain it today.

大おおきな is more conceptual while 大おおきい is more factual.

If you are planning to buy a big bag, you can walk into a shop and say either:

大おおきな カバンを ください。
or
大おおきい カバンを ください。

If there is no context to think of, the above 2 sentences are almost the same. However, if they brought out 2 bags of difference sizes and if you want a bigger one, you say:

大おおきい カバンを ください。（or more like 大おおきいの (= the big one) or 大おおきい方ほう (= the bigger one) を ください。）

When you talk about the actual size, 大おおきい is preferred over 大おおきな.

大おおきな is more preferred when the subsequent noun is for something conceptual rather than real.

エマさんは 大おおきな 夢ゆめを 追おっています。
Emma is chasing a big dream.

ダンさんは 大おおきな プロジェクトに 取とり組くんでいます。
Dan is working on a big project.

Some native speakers may say they would use 大おおきい instead of 大おおきな in the above sentences, but I think more native speakers will choose 大おおきな over 大おおきい here.

However, if you swap 夢ゆめ (dream – conceptual) with 馬うま (a horse – real), プロジェクト (project – conceptual) with 絵え (painting – real), most native speakers will find 大おおきい more preferable than 大おおきな.

エマさんは 大おおきい 馬うまを 追おっています。
Emma is chasing a big horse.

ダンさんは 大おおきい 絵えに 取とり組くんでいます。
Dan is working on a big painting.

Again, using 大おおきな instead of 大おおきい here is not wrong either and in fact some native speakers may say that they prefer that way.

Even though the differences are very small, based on the above 2 points, let’s talk about the second question I asked. Before I start talking about the meaning, though, I will first apologize for the strange choice of words. Today’s example sentences are not great at all. However, in order to make my point, I needed to pick a rather unusual combination of words.

a. ジョンさんの 心こころの 友達ともだちは 大おおきい。
 John’s soul mate is big. (In this case 大おおきい more likely means “physically big” rather than anything else)

c. ジョンさんには 大おおきい 心こころの 友達ともだちが いる。
In this sentence 大おおきい sounds more like describing 友達ともだち (real) rather than 心こころ(conceptual), so the whole sentence means more like: John has a big soul mate.
And in this case 大おおきい can be for “physically big” but can also be for “significant” or “important.”

d. ジョンさんには 大おおきな 心こころの 友達ともだちが いる。
In this sentence 大おおきな sounds more like describing 心こころ (conceptual) rather than 友達ともだち (real), so the whole sentence means more like: John has a friend with a big heart.

These interpretations of sentences, especially of c and d, are not conclusive and final. Depending on the context and where the stress is placed, they can be interpreted either way, but I just wanted to show that there is some difference between 大おおきい and 大おおきな.