Japanese has two main classes of adjectives.

  • Pure adjectives (形容詞 keiyōshi, aka. i-type adjective): these are very similar to verbs, having roots and conjugating stem forms.
  • Adjectival nouns (形容動詞 keiyōdōshi, aka na-type adjective): these are grammatical nouns (though not necessarily legally possible as nouns) that are affixed with -na or-no to form the adjective.

All pure adjectives except for いい (ii, good) have regular conjugations, and ii is irregular only in the fact that it is a corruption of the regular adjective 良い (yoi) which manifests itself in the conjugations. All adjectival nouns conjugate regularly.

-Pure adjectives-Adjectival nouns
-安・い (yasu.)い・い (i.)静か- (shizuka-)
Attributive form 1

(連体形 rentaikei)

安い (.i)いい (.i)静かな (-na)
Terminal form 1

(終止形 shuushikei)

安い (.i)いい (.i)静かだ (-da)
Continuative form

(連用形 ren'youkei)

安く (.ku)良く (yo.ku)*静かで (-de)
Imperfective form

(未然形 mizenkei)

安かろ (.karo)良かろ (yo.karo)*静かだろ (-daro)
Hypothetical form

(仮定形 kateikei)

安けれ (.kere)良けれ (yo.kere)*静かなら (-nara)
Imperative form 2

(命令形 meireikei)

安かれ (.kare)良かれ (yo.kare)静かなれ (-nare)

  1. The attributive and terminal forms were formerly 安き (.ki) and 安し (.shi), respectively; in modern Japanese, these are used productively for stylistic reasons only, although many set phrases such as 名無し (nanashi, anonymous) and よし (yoshi, sometimes written yosh', general positive interjection) derive from them.
  2. The imperative form is extremely rare in modern Japanese, restricted to set patterns like 遅かれ早かれ (osokare hayakare, sooner or later), where they are treated as adverbial phrases! It is impossible for an imperative form to be in a predicate position.

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

-Pure adjectives 安い (yasui)-Adjectival nouns 静か (shizuka)-
Plain polite nonpastterm. + copula です (desu)安いです

yasui desu

root + copula です (desu)静かです

shizuka desu

informal pastcont. + あった (atta)

(u + a collapse)



cont. + あった (atta)

(e + a collapse)


shizuka d.atta

informal negative


cont. + (は)ない ((wa) nai) 1安く(は)ない


cont. + (は)ない ((wa) nai)静かで(は)ない

shizuka de (wa) nai

informal negative


cont. + (は)なかった ((wa)

nakatta) 1



cont. + (は)なかった ((wa) nakatta)静かで(は)なかった

shizuka de (wa) nakatta

polite negative


inf. neg. non-past +

copula です (desu) 1


yasukunai desu

inf. cont + (は)ありません

((wa) arimasen)


shizuka de wa arimasen

polite negative


inf. neg. past + copula

です (desu) 1


yasukunakatta desu

inf. cont + (は)ありませんでした

((wa) arimasen deshita)


shizuka de wa

arimasen deshita

---inf. neg. past + なかったです

(nakatta desu) 1

inf. neg. past + なかったです (nakatta desu) 1


shizuka de wa

nakatta desu

-te formcont. + て (te)安くて



shizuka de

conditional 2hyp. + ば (ba)安ければ

hyp. (+ ば (ba))静かなら(ば)

shizuka nara(ba)

provisional 2inf. past + ら (ra)安かったら


inf. past + ら (ra)静かだったら

shizuka datta.ra

volitional 3imperf. + う (u)安かろう (yasukarō)imperf. + う (u)

= root + だろう (darō)


(shizuka darō)



root + に (ni)静かに

shizuka ni

degree (-ness)root + さ (sa)安さ


root + sa静かさ


  1. Note that these are just forms of the pure adjective ない (nai)
  2. See the note on hypothetical forms (Part 4).
  3. 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 (yokarō, OK (lit: let it be good)) in response to a report or request.
Adjectives too are governed by euphonic rules in certain cases, as noted in the section on it below. For the polite negatives of adjectival nouns, see also the section below on the copula だ (da).

Japanese Grammar Contents

  • Part 1: Textual classifications; nouns, pronouns, and other deictics
  • Part 2: Conjugable words: verbs
  • Part 3: Conjugable words: adjectives
  • Part 4: Conjugable words: the copula だ da
  • Part 5: Euphonic changes, colloquial contractions
  • Part 6: Adverbs, sound symbolism, conjunctions and interjections
  • Part 7: Particles
  • Part 8: Auxiliary verbs