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Japanese has two main classes of words that function the same as adjectives in English.

Pure adjectives (形容詞; けいようし)
Also known as い-adjectives these are distinctive as their attributive form always ends with the syllable "い". Many nouns (such as 白 (しろ e. the colour white) become pure adjectives when appended with an い: 白い (しろい, e. white). Learners must beware, though, because several な-adjectives also end with the same い when rendered in kana (e.g. きらい, きれい).
Examples of pure adjectives are the colours 赤い (あかい, e. red) and 青い (あおい, e. blue), 高い (たかい, e. high, tall) 小さい (ちいさい, e. small), 重い (おもい, e. heavy) and 軽い (かるい, e. light).
Adjectival nouns (形容動詞; けいようどうし)
Also known as な-adjective these are grammatical nouns that form adjectives when affixed with "〜な". Technically, the な pseudoparticle comes from a contraction of "なる", the attributive form of the classical Japanese copula "なり".
Examples of adjectival nouns are 綺麗 (きれい, e. pretty), 静か (しずか, e. quiet) and 素敵 (すてき, e. lovely).

This paragraph should be removed because いい is NOT a different adjective than よい. よい has いい as a popular form and you can use いい and よい interchangeably in these forms anytime anywhere. Everyone should stop using this ridiculous explanation: There is only a single irregular adjective; the pure adjective "良い" (いい, e. good). Even at that "良い" conjugates regularly and the only irregularity arises from the fact that it's a corruption of "良い" read as "よい". Conjugations that include the attributive い are read いい while others are read よ〜 (e.g. よく, よかったら, etc.).

Basic conjugations[edit | edit source]

Like verbs, we can enumerate some common conjugations of adjectives. Also, "いい" isn't special-cased, because all conjugations are identical to "よい".

It should not come as a surprise that the な-adjectives — being grammatical nouns — "conjugate" by having the copula added. Exceptions are the plain present positive, where the copula is omitted, and the polite past negative which has an alternative reading.

present positive past positive present negative past negative
plain 〜だった 〜ではない 〜ではなかった
polite 〜です 〜でした 〜ではありません 〜ではありませんでした


The い-adjectives have a somewhat simple conjugation pattern. The politeness is only determined by whether the (polite present positive, in all tenses) copula is added.

present positive past positive present negative past negative
plain 〜い 〜かった 〜くない




polite 〜いです 〜かったです 〜くないです 〜くなかったです

More forms[edit | edit source]

It can be useful to define a few stem forms for adjectives as these form building blocks for other forms.

Pure Adjectives Adjectival Nouns
Attributive form (連体形) 〜い 〜な
Terminal form (終止形) 〜い 〜だ
Continuative form (連用形) 〜く 〜で
Imperfective form (未然形) 〜かろ 〜だろ
Hypothetical form (仮定形) 〜けれ 〜なら
Imperative form (命令形 ) 〜かれ 〜なれ

These then form the following derived forms:

Pure Adjectives Adjectival Nouns
て-form cont. + て 〜くて cont. 〜で
conditional hyp. + ば 〜ければ hyp. + ば 〜なら(ば)
provisional inf. past + ら 〜かったら inf. past + ら 〜だったら
volitional[1] imperf. + う 〜かろう imperf. + う 〜だろう
adverbial cont. 〜く cont.+に 〜に
degree (-ness) root + さ 〜さ root + さ 〜さ

Adjectives too are governed by euphonic rules in certain cases. For the polite negatives of adjectival nouns, see also the section below on the copula.

Imperative[edit | edit source]

The imperative form is extremely rare in modern Japanese, restricted to set patterns like (おそ)かれ(はや)かれ (e. sooner or later) where they are treated as adverbial phrases! It is impossible for an imperative form to be in a predicate position.

Hypotheticals[edit | edit source]

The conditional and provisional forms are used to make conditional statements. There is a slight nuance to the two which is discussed further in the conditionals lesson.

Notes[edit | edit source]

  1. Since most adjectives describe non-volitional conditions, the volitional form is interpreted as "it is possible", if sensible. In some rare cases it is semi-volitional: 良かろう, meaning OK (lit: let it be good), in response to a report or request.