い-adjectives

Level 1Sounds Like i

い-adjectives (形容詞（けいようし）) describe qualities or states. They are unique because they contain the meaning of 'is/am/are' within themselves and change their endings to show past tense, negative meanings, or to connect with other words.

How It Works

い-adjectives are a core part of Japanese. They are easily identified because they always end in the hiragana い (as okurigana). Be careful: some な-adjectives like きれい or 有名（ゆうめい） end in the sound 'i' but are not い-adjectives.

1. Two Main Uses:

  • Attributive: Placing the adjective directly before a noun. Unlike な-adjectives, they never use な (e.g., 高いビル - a tall building).
  • Predicative: Using the adjective to end a sentence (e.g., ビルは高い - The building is tall).

2. Conjugation Basics:
To change the meaning, you drop the final い and add a new suffix:

  • Present Negative: Drop い, add 〜くない (e.g., 高くない - not tall).
  • Past Affirmative: Drop い, add 〜かった (e.g., 高かった - was tall).
  • Past Negative: Drop い, add 〜くなかった (e.g., 高くなかった - wasn't tall).

3. Politeness:
To make an い-adjective polite, you first conjugate it to the desired plain form, then add です.

  • Polite Present: 高い + です
  • Polite Negative: 高くない + です (or the more formal 高くありません)
  • Polite Past: 高かった + です

4. Connecting and Modifying:

  • Te-form: Drop い, add 〜くて to connect adjectives (e.g., 安くておいしい - cheap and delicious).
  • Adverbial: Drop い, add 〜く to modify verbs (e.g., 速く走る - run fast).

5. The 'ii' Exception:
The word for 'good,' いい, is irregular. Its formal dictionary form is 良い（よい）. While the present form is いい, all other conjugations must use the stem よ (e.g., よく、よくない、よかった).

Examples (4)

  1. このお茶はとても熱いです。

    This tea is very hot.

    Word by Word: This tea (topic) very hot is.

    Here, the adjective 熱い（あつい） ends the sentence politely by adding です.

  2. 昨日はあまり寒くなかった。

    It wasn't very cold yesterday.

    Word by Word: Yesterday (topic) not-very cold-was-not.

    This uses the past negative form of 寒い（さむい） in a casual setting.

  3. 新しい車を買いました。

    I bought a new car.

    Word by Word: New car (object) bought.

    The adjective 新しい（あたらしい） modifies the noun 車（くるま） directly.

  4. テストはよくなかったです。

    The test was not good.

    Word by Word: Test (topic) good-not was.

    This shows the irregular conjugation of いい (good), which changes to よく before adding かった or ない.

Common Mistakes

  • Using the copula だ with い-adjectives in casual speech.

    この本は高いだ。
    この本は高い。

    Unlike nouns or な-adjectives, い-adjectives already contain the 'is' meaning. You should never use だ with them in casual speech.

  • Treating な-adjectives that end in the 'ei' sound as い-adjectives.

    部屋はきれいかった。
    部屋はきれいだった。

    Words like きれい (pretty) and 有名（ゆうめい - famous） are な-adjectives. Even though they end in the sound 'i', they do not end in the hiragana okurigana い. They conjugate like nouns using 〜だった.

  • Incorrect past tense in polite speech.

    寒いですした。
    寒かったです。

    A common mistake is trying to make the copula past tense (like ですした). Instead, you must conjugate the い-adjective itself into the past form (〜かった) before adding です.

How It Connects

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い-adjectivesLevel 1

Learn This First

To understand い-adjectives, you first need to grasp the general concept of adjectives and be able to read hiragana, as their classification and conjugation depend on the final 'い' character.

Learn Next

Patterns that build on this one.

And 9 more in the full list.