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.
  • (ぬる)(みず)
    Lukewarm water.
  • (せま)(みち)
    Narrow road.
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.
  • バナナ(きら)い。
    I also don't like bananas.
  • (みず)きれい。
    The water is clear.
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
    Japan's roads are narrow.
  • 温泉(おんせん)風呂(ふろ)(あつ)です
    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.


  • (あつ)です

    It is hot.

  • 今日(きょう)(あつ)です

    It is hot today.

  • (さむ)です

    It is cold.

  • これ(たの)しいです

    This is fun.

  • (あたら)しい(くるま)

    A new car.

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い-Adjectives – Grammar Discussion

Most Recent Replies (36 in total)

  • mietolim


    About 1 month ago

    I’m being quizzed about this grammar point without Bunpro providing the exact Japanese word that it wants me to use, which is a bit annoying as the point of this exercise is to know how to conjugate the words. For example I had to fill in “The blanket is hot”, but the word that Bunpro wants me to use, 温かい, seems to mean warm, so it’s a bit confusing why the word isn’t just provided as part of the exercise, especially since there isn’t any explanation why that specific word should be used as opposed to any other alternative.

  • Motifier


    About 1 month ago

    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


    About 1 month ago

    Thank you for providing the info!

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