Grammar Info

N5 Lesson 1: 10/12


Adjectives ending in い

い-Adjectives cannot be used with だ


おおき, おいし, はや


  • Part of Speech


  • Word Type

    Independent Word

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  • 品詞


  • 単語の種類


  • 使用域


About い-Adjectives

In Japanese い-Adjectives are known as 'form containing words', and are used to describe nouns. All い-Adjectives end in い in their base form.

As mentioned, all い-Adjectives end in い in their base form. However, not all words ending in い are い-Adjectives. Let's take a look at some of the words that are commonly mistaken for い-Adjectives.

In きれい's case, it actually comes from the kanji structure 綺麗(きれい), with い being part of the kanji itself. This is never the case with い-Adjectives, where the い will always be outside of the kanji. Due to the kanji for 綺麗(きれい) being somewhat difficult, this word is often written in hiragana or katakana, which leads to confusion for learners. Unfortunately there is no rule for distinguishing which words ending in い are not い-Adjectives, but thankfully, there are not very many of them, so it won't be long before you become familiar with them.


Unlike な-Adjectives, い-Adjectives must never be followed by . This is due to only being able to conjugate with nouns (which な-Adjectives originally are). Instead, です is used with い-Adjectives to make them sound more polite.

  • 日本(みち)(せま)です。 (Natural Japanese)
    Japan's roads are narrow.
  • 温泉(おんせん)風呂(ふろ)(あつ)。 (Unnatural Japanese)
    The onsen's baths are hot.

Fun Fact

Although using です with い-Adjectives is very common, it is actually incorrect Japanese. As です is simply a polite variation of , it follows all of the same conjugation rules as . This means that it should only be attached to nouns and な-Adjectives. However, as most Japanese natives do not know this rule, it is widely considered natural to use.




    It is hot.


    It is hot today.


    It is cold.


    This is fun.


    A new car.

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い-Adjectives – Grammar Discussion

Most Recent Replies (37 in total)

  • Motifier


    It was provided before and they’ve said that theyll be fixing it asap, no idea what that time frame is though… - い-Adjective No longer show the word to right? - #2 by Asher

  • mietolim


    Thank you for providing the info!

  • Guguru-san


    I’m a little confused about the example phrase 新しい車。 Wouldn’t either -い or -た have to go at the end to make it a correct sentence? I’m thinking either 新しい車だ or 車は新しい。Any thoughts?

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