1A pre-noun word (rentaishi) placed before a noun to indicate that something is large in size or great in degree; unlike 大きい, it can only modify nouns directly and cannot be used as a predicate.
あの大きな木は百年以上前からあるそうだ。
That big tree is said to have been there for over a hundred years.
大きな声で挨拶しましょう。
Let's greet each other in a loud voice.
これは会社にとって大きな問題だ。
This is a big problem for the company.
彼女は大きな夢を持っている。
She has big dreams.