Lesson 10
Adjectives: い-Adjectives
Introduction to い-Adjectives
In Japanese, adjectives are divided into two distinct grammatical categories: い-adjectives (i-adjectives) and な-adjectives (na-adjectives). True い-adjectives always end with the hiragana syllable い (i) in their dictionary form, such as あたらしい (atarashii - new), たかい (takai - expensive/tall), and さむい (samui - cold). Be careful with a few exceptions like きれい (kirei - pretty/clean) and ゆうめい (yuumei - famous); although they end with the sound 'i', they are な-adjectives because their kanji spellings end in 'e' followed by 'i'.
い-adjectives are unique because they behave almost like verbs: they inflect (conjugate) directly on their stems to express tense and polarity. When placed at the end of a sentence in polite speech, you simply add です (desu) after the adjective to show politeness, as in この ほん は おもしろい です (Kono hon wa omoshiroi desu - This book is interesting).
Present Tense: Affirmative and Negative
To make a polite present affirmative statement with an い-adjective, keep the dictionary form ending in い and follow it with です. For example: きょう は あつい です (Kyou wa atsui desu - Today is hot). Here, あつい (atsui) retains its ending.
To make an い-adjective negative ('is not...'), you drop the final い and add くない (kunai). In polite speech, add です after くない, resulting in ~くない です (~kunai desu). For example, to say 'it is not hot', start with あつい (atsui), drop the い to get あつ-, and attach くない です to form あつくない です (atsukunai desu). Another formal alternative is ~く ありません (~ku arimasen), such as あつく ありません (atsuku arimasen).
Past Tense: Affirmative and Negative
Because い-adjectives conjugate on their own, you never change です into でした to make an adjective past tense. Instead, conjugate the adjective itself. For the past affirmative ('was...'), drop the final い and attach かった です (~katta desu). For example, ふるい (furui - old) becomes ふるかった です (furukatta desu - was old). Saying ふるい でした is a very common beginner mistake and is grammatically incorrect.
For the past negative ('was not...'), start with the negative stem ~く and add なかった です (~nakatta desu). Therefore, the full pattern is dropping the final い and adding ~くなかった です (~kunakatta desu). For example, さむい (samui - cold) becomes さむくなかった です (samukunakatta desu - was not cold). Alternatively, the more formal option is ~く ありませんでした (~ku arimasendeshita), yielding さむく ありませんでした.
The Irregular Adjective: いい (Good)
The Japanese word for 'good' or 'nice' is いい (ii). However, this adjective historically derives from よい (yoi). While いい is commonly used for the present affirmative form (いい です - ii desu), all other conjugated forms must be built from the stem よ (yo-).
Whenever you conjugate this word, replace い with the base よ- before adding standard endings: the negative form is よくない です (yokunai desu - not good), the past affirmative is よかった です (yokatta desu - was good), and the past negative is よくなかった です (yokunakatta desu - was not good). Forms like いけない or いかった are completely incorrect for this meaning.
Modifying Nouns and Connecting Adjectives
When an い-adjective describes a noun directly, place it directly in front of the noun without any particle. For example, おおきい いぬ (ookii inu) means 'a big dog', and おいしい おちゃ (oishii ocha) means 'delicious green tea'. The adjective keeps its final い when modifying nouns in the present tense.
If you want to string multiple adjectives together to say something is both 'X and Y', you change the first い-adjective into its て-form by dropping the final い and attaching ~くて (~kute). For example, to combine やすい (yasui - cheap) and おいしい (oishii - delicious), say: この みせ は やすくて おいしい です (Kono mise wa yasukute oishii desu - This restaurant is cheap and delicious).
Lesson quiz · 1 of 5
What is the polite present negative form of さむい (samui - cold)?