This is the 5908th most frequent Japanese word.
むずかしい
Difficult.
The word 'むずかしい' is used to describe the problem as challenging or requiring significant effort to solve.
この問題はむずかしいです。
This problem is difficult.
Here, 'むずかしい' is used to indicate the complexity of understanding the explanation.
彼の説明は少しむずかしいですけど、役に立ちました。
His explanation is a bit difficult, but it was helpful.
In this sentence, 'むずかしい' refers to books that are intellectually challenging or advanced.