な-adjectives

Adjectives (形容詞, “keiyōshi”) play a crucial role in the Japanese language, helping to describe people, objects, feelings, and situations.

Firstly, let’s talk about this in English. We don’t simply use adjectives to add extra descriptions to nouns just for the sake of it, but they actually play a vital role in how we express ourselves in the language. Adjectives help convey specific details and characteristics, allowing us to communicate more clearly and effectively. They give us the power to paint a more vivid picture and to provide more nuance to our speech or writing.

For example, when we say “fast car,” we’re not just talking about a car, but a car with a particular characteristic—its speed. Similarly, when we describe a “big house,” we’re emphasizing the size of the house, which can evoke a sense of grandeur or spaciousness. In the case of “hard metal,” the adjective “hard” conveys the physical quality of the metal, distinguishing it from softer materials. Without adjectives, our language would be much more basic and less expressive. These descriptive words are essential for adding depth to our communication and making it more engaging and specific.

Now in Japanese, adjectives are categorized into い-adjectives (い形容詞, “ikeiyoshi”) and な-adjectives (な形容詞, “ikeiyoshi”). We will focus on な-adjectives, their conjugations, and how to use them in sentences.

Fundamentals

Unlike い-adjectives, な-adjectives do not end in 〜い hiragana. They also behave similarly to nouns and require な when directly modifying a noun.

Examples

When modifying a noun, な-adjectives must include な between the adjective and the noun.

For example:

便利なアプリ 
(benri na apuri)
"A convenient app"

元気な俳優
(yūmei na haiyū)
"A healthy actor"

Conjugation

Since な-adjectives function similarly to nouns, their conjugation is simpler than い-adjectives. They typically use です or だ for formal/informal speech.

Unlike い-adjectives, な-adjectives do not change internally.

Present Tense　(Dictionary Form)

When you present the adjective as it is without changing the tense, the adjective will be in present tense by default.

For example:

静かだ (shizuka da)

Present Negative　(〜ではない / 〜じゃない)

To form the negative, add ではない (plain) or ではありません (polite).

Casual
静かではない (shizuka de wa nai, "not quiet")


Polite
静かではありません (shizuka de wa arimasen, "not quiet")

You may also see じゃない (less formal) instead of ではない:

静かじゃない (shizuka ja nai, "not quiet") – Less formal

Casual
静かだった (shizuka datta, "was quiet")

Polite
静かでした (shizuka deshita, "was quite")

Past Negative　(〜ではなかった / 〜じゃなかった)

To form the past negative, use ではなかった (plain) or ではありませんでした (polite).

Casual
静かではなかった (shizuka de wa nakatta, "was not quiet")

Polite
静かではありませんでした (shizuka de wa arimasen deshita, "was not quiet")

Other Grammar Structures

Listing multiple adjectives（〜で）

To link multiple な-adjectives or use them to describe an action, replace な with で.

For example:

彼は元気で、親切です。 
(Kare wa genki de, shinsetsu desu.) 
"He is energetic and kind."

その問題は簡単で、便利です。 
(Sono mondai wa kantan de, benri desu.) 
"That problem is simple and convenient."

Becoming Something (になる)

To express a change (e.g., becoming famous, becoming quiet), use 〜になる.

Example Sentences:

彼は有名になりました。 
(Kare wa yūmei ni narimashita.) 
"He became famous."

町が静かになった。 
(Machi ga shizuka ni natta.) 
"The town became quiet."