Japanese Adjectives

This lesson is an introduction to the different classes of Japanese adjectives and how to use them as predicates and modifiers.

Recommended Background:

Except for “Questions and Negation”, these topics are not strictly necessary in order to understand this lesson, but the following lessons will assume that you are familiar with all of them.

What is an Adjective?

Linguistically, adjectives are not as fundamental as nouns and verbs, and depending on the language, might behave more like one or the other. Either way, they serve two main functions:

  1. As noun modifiers – where the adjective is adjacent to the noun
  2. As predicates to a sentence (giving a property to the subject) – where the adjective takes the verb position of the sentence, possibly requiring a copula

In either case, the basic purpose of the adjective is to give a property to the noun.

Japanese is interesting in that it has multiple distinct classes with a function similar to English adjectives, and all but one inflect to show characteristics like tense and negation. English adjectives also inflect, but only two a very limited extent: -er (more) and -est (most), and only certain adjectives can use these suffixes anyway.


This first group is the i-adjectives, so called because they all end with an い ‘i’. These adjectives are a specialized class of verbs, each with a meaning of “to be [some property]“, and for this reason they are also called adjectival verbs.

When an i-adjective is placed in front of a noun, it modifies the noun directly, and when placed at the end of the sentence, it becomes a predicate.

I-Adj. as Modifier I-Adj. as Predicate
Hiragana おおきい やま  やまは おおきい。
Romaji ookii yama  Yama wa ookii.
Gloss be-big mountain  mountain TOP be-big
Translation a big mountain  The mountain is big.

This makes a lot of sense considering that normal Japanese verbs also become modifiers when placed in front of a noun.

Hiragana Romaji Gloss Translation
にほんごの はなせる アメリカじん nihongo no hanaseru Amerika-jin can-speak-Japanese American an American who can speak Japanese
たべている やまださん tabeteiru Yamada-san eating Yamada Yamada, who is eating
ぬれた いぬ nureta inu got-wet dog a wet dog

In the case of the last example, the past tense of nureru (to get wet) is in fact the only way to say the equivalent of the English adjective “wet”.

When using an i-adjective for the predicate function in formal speech, simply add desu afterward to make the sentence polite.

Hiragana Romaji Gloss Translation
むしは ちいさいです。 Mushiwa chiisai desu. bug TOP be-small ()-polite The bug is small.

This is one of the cases where desu is not actually a copula, since the adjective already includes the meaning of “to be”. Compare this to the following:

Hiragana Romaji Gloss Translation
ちいさい むしです。 Chiisai mushi desu. be-small bug be-POLITE It’s a small bug.

In this case, desu is serving its usual function.


The second group, the na-adjectives, are followed by な ‘na’ when used to modify nouns, and by the copula when used to predicate a sentence.

Hiragana Romaji Gloss Translation
きれいな はな kirei na hana pretty flower a pretty flower
はなは きれい だ。 Hana wa kirei da. flower TOP pretty be-PRES The flower is pretty.

In formal speech, da in the predicate is replaced with desu.

Hiragana Romaji Gloss Translation
はなは きれい です。 Hana wa kirei desu. flower TOP pretty be-PRES The flower is pretty.

The result of this is that in formal speech, both i- and na-adjectives will be followed by desu in the predicate position, though the reasons in each case are different.

The root of a na-adjective also functions as a noun.

とくべつな tokubetsu na special
とくべつ tokubetsu specialty

For this reason na-adjectives are also known as adjectival nouns.

Note: You may also hear i-adjectives referred to simply as “adjectives” (keiyoushi) and na-adjectives referred to as “adjectival verbs” (keiyou doushi), both terms from traditional Japanese grammar. Even more confusing, “adjectival verb” is also sometimes used to refer to da/desu itself, although in this case the term actually makes a bit of sense. Because of these complications, I will always use the unambiguous terms “i-adjective” and “na-adjective”.

The vast majority of Japanese adjectives are either i-adjectives or na-adjectives. But why have two classes in the first place?

The reason for this division is mainly historical. I-adjectives come directly from Old Japanese, while na-adjectives are derived from Chinese roots (i.e., they’re Kanji compounds). And for whatever reason, Japanese allows new na-adjectives to be created, but not new i-adjectives. The result of this is that basic words like “big” and “good” tend to be i-adjectives, and more complex or abstract words are almost always na-adjectives.


Another group is the no-adjectives. These words are true nouns, and take the particle no when used as modifiers and use the copula to predicate a sentence.

Hiragana Romaji Gloss Translation
みどり midori green the color green
みどりの ほん midori no hon green’s book a green book
ほんは みどりだ。 Hon wa midori da. book TOP green be-PRES The book is green.

Essentially, the only difference between no-adjectives and na-adjectives is the particle used when they appear as modifiers.

As for the difference between no-adjectives and ordinary nouns, there really is none. Rather, the term is a convenient way to describe nouns whose meaning is more in line with what we think of as an adjective.


The final group of adjectives are the attributives (rentaishi), which are few in number. These adjectives can only be used to modify nouns, never to predicate a sentence.

Two such adjectives are ookina (big) and chiisana (small), which mean the same thing as the i-adjectives ookii and chiisai. Ko-so-a-do words like kono (this) and sono (that) can also be considered attributives, since they are used only as modifiers.

Negative Form for Adjectives

We won’t get into the details of adjective conjugation here, but we will look at one particular conjugation: negative form.

  • To change an i-adjective into its negative form, replace the -i with -ku nai, or in polite form, either -ku nai desu or -ku arimasen, analogous the the two negative forms of desu. Again, -ku nai desu expresses stronger negation than -ku arimasen.
  • For na- and no-adjectives, simply replace da/desu with the appropriate negative form.
  • Attributives cannot inflect.
Negative Form for Adjectives
i-adjectives na/no-adjectives
Plain Present
[stem]+i  [stem] da
[stem]+ku nai  [stem] dewa na (ja nai)
Polite Present
[stem]+i desu  [stem] desu
[stem]+ku nai desu/arimasen  [stem] dewa nai desu/ dewa arimasen (ja nai/ ja arimasen)


  • The ku you see here one of several possible inflections that an i-adjective can take (the “continuative form” in traditional grammar), and nai/arimasen are auxiliaries that can be added to this particular inflection, both with the meaning of negation.
  • The stem of a na/no adjective doesn’t actually inflect. In this case, only the copula is changed.

Any negative form can be used in the predicate position with no changes to the rest of the sentence. This is true for any other conjugations as well.

Hiragana Romaji Gloss Translation
ケーキは おいしくないです。 Keeki wa oishiku nai desu. cake TOP delicious not-be ()-polite The cake is not delicious. (= no good)
バスは べんりじゃありません。 Basu wa benri ja arimasen. bus TOP convenient not-be-polite The bus is not convenient.

You can also use the plain negative form as a modifier.

Hiragana Romaji Gloss Translation
おいしくない ケーキ oishiku nai keeki delicious not-be cake a cake that is not delicious
べんりじゃない バス benri ja nai basu convenient not-be bus a bus that is not convenient

You can actually do this with no-adjectives and ordinary nouns as well.

Also, note how in English we need to add “that” in order to use a modified adjective in a noun phrase. This is because English does not allow verbs or verb phrases to directly precede nouns like in Japanese.


A full discussion of adjective conjugation will come after you’ve been introduced to verbs. In the meantime, the next couple lessons will focus on using adjectives.

What Next?

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