Japanese adjectives

i-adjectives end with い (i) (but never えい, ei) in base form. They may predicate sentences and inflect for past, negative, etc. As they head verb phrases, they can be considered a type of verbal (verb-like part of speech) and inflect in an identical manner as the negative form of verbs. Their inflections are different and not so numerous as full verbs.

i-adjectives are considered verbs because they inflect with the same bases as verbs and their respective usages: irrealis (未然形 mizenkei), continuative (連用形 renyōkei), terminal (終止形 shuushikei), attributive (連体形 rentaikei), hypothetical (仮定形 kateikei), and imperative (命令形 meireikei).

Among the six bases of verbs for i-adjectives, there exist two sets of inflection paradigms: a "plain" or "true" conjugation, and what is known as a kari-conjugation (カリ活用 kari-katsuyō), which is the result of the contraction between the "plain" continuative form 〜く (ku) and the verb あり (有り, 在り) ari, meaning "to exist", "to have", or "to be". Due to this, the kari-conjugation paradigm resembles that of the r-irregular conjugation paradigm (ラ行変格活用 ra-gyō henkaku katsuyō) of あり ari, however the hypothetical (historically the 已然形 izenkei) is 〜けれ kere instead of 〜かれ kare (used historically, and also the imperative base).

The stem of i-adjectives can combine (prepend on the left), similar to the continuative form of verbs, though this is less common than for verbs. Conversely, nouns or verb stems can sometimes prepend i-adjectives, or two i-adjectives can combine, forming compound modifiers; these are much less common than Japanese compound verbs. Common examples include omo-shiro-i (面白い, interesting) "face-whitening" (noun + i-adjective), and zuru-gashiko-i (狡賢い, sly) "crafty-clever" (i-adjective stem + i-adjective); while haya-tochiri (早とちり, going off half-cocked) "fast-fumble" (i-adjective stem + verb stem) shows an adjective stem joining to form a noun.

A number of i-adjectives end in -shii (〜しい) (sometimes written -sii). These are overwhelmingly words for feelings, like kanashii (悲しい, sad) or ureshii (嬉しい, happy). These were originally a separate class of adjectives, dating at least to Old Japanese (see Old Japanese adjectives), where the two classes are known as -ku (〜く) and -shiku (〜しく), corresponding to -i and -shii. However, they merged over the course of Late Middle Japanese (see Late Middle Japanese adjectives), and now shii-adjectives are simply a form of i-adjectives. The distinction, although no longer meaningful in pronunciation, is still reflected by the writing system, where し is still written out in hiragana, as in atarashii (新しい, new).

Adjectives that end in -jii (〜じい) are also considered -shii adjectives, such as susamajii (凄まじい, terrific), and historically onaji (同じ, same), which was initially a -shii adjective, and the classical negative volitional auxiliary maji (まじ).

na-adjectives always occur with a form of the copula, traditionally considered part of the na-adjective itself. The only syntactical difference between nouns and na-adjective is in the attributive form, where nouns take の (no) and adjectives take な (na). This has led many linguists to consider them a type of nominal (noun-like part of speech). Through use of inflected forms of the copula, these words can also predicate sentences and inflect for past, negative, etc.

Notably, na-adjective are distinct from regular nouns, in that they cannot be used as the topic, subject, or object. To function in these roles, the na-adjectives must include the nominalizing suffix さ (-sa), broadly similar to the English suffix -ness that is used to create nouns from adjectives.

There are a number of na-adjectives ending in 〜やか (-yaka), particularly for subjective words (compare i-adjectives ending in -shii). This is believed to be a combination of the two suffixes 〜や (-ya) and 〜か (-ka), where 〜や meant "softness" and 〜か meant "apparent, visible" (similar to modern 〜そう, -sō, which is also followed by 〜な), hence the combination 〜やか meant "appears somewhat ..., looks slightly ...". This was believed to have been used in the Nara era, and have become particularly popular in the Heian period, but is no longer productive.[1] In some cases the original word is now only used (or almost always used) in the 〜やか form, such as 鮮やか (aza-yaka, "vivid, brilliant"), 穏やか (oda-yaka, "calm, gentle"), and 爽やか (sawa-yaka, "fresh, clear"), while in other cases the word is used in isolation, such as 雅 (miyabi, "elegant, graceful"), which is used alongside 雅やか (miyabi-yaka, "elegant, graceful"), and in other cases a related word also exists, such as 賑やか (nigi-yaka, "bustling, busy") and the verb 賑わう (nigi-wau, "be bustling, be busy"). The most basic of these is 賑やか (nigi-yaka, "bustling, busy"), but many of these are everyday words. Due to the 〜やか being originally a suffix, it is written as okurigana, even though the compound word may now be a fixed unit.

Similarly, there are also a few na-adjectives ending in 〜らか (-raka), of similar origin. These are generally less subjective, but declined in popularity relative to the 〜やか construction in the Heian period[1] Notable examples include 明らか (aki-raka, "clear, obvious") and 柔らか／軟らか (yawa-raka, "soft, gentle"). As with 〜やか words, the 〜らか is written out as okurigana.

A variant of na-adjectives exist, which take 〜たる (-taru) when functioning attributively (as an adjective, modifying a noun), and 〜と (-to) when functioning adverbially (when modifying a verb),[2] instead of the 〜な (-na) and 〜に (-ni) which are mostly used with na-adjectives. taru-adjectives do not predicate a sentence (they cannot end a sentence, as verbs and i-adjectives can) or take the copula (as na-adjectives and nouns can), but must modify a noun or verb. Note that sometimes na-adjectives take a 〜と, and Japanese sound symbolisms generally take a (sometimes optional) 〜と, though these are different word classes.

There are very few of these words,[3] and they usually are considered somewhat stiff or archaic; this word class is generally not covered in textbooks for foreign language learners of Japanese. One of the most common is 堂々 (dōdō, "magnificent, stately"). These are referred to in Japanese as ト・タル形容動詞 (to, taru keiyōdōshi) or タルト型活用 (taruto-kata katsuyō – “taru, to form conjugation”).

See 形容動詞#「タルト」型活用 for discussion in Japanese. Historically, these developed in Late Old Japanese as a variant of na-adjectives,[4][5] but the form mostly died out; the remaining taru-adjectives are fossils, and conjugationally defective, having formerly held the pattern of the r-irregular class, like its component あり.

There are also a few naru-adjectives such as 単なる (tannaru, "mere, simple") or 聖なる (seinaru, "holy"), which developed similarly to taru-adjectives.[4] As with taru-adjectives, these cannot predicate or take the copula, but must modify a noun (though generally not a verb – many of these only modify nouns via なる, not verbs via ×に), and often occur in set phrases, such as Mother Nature (母なる自然, haha-naru shizen). In Late Old Japanese, tari-adjectives developed as a variant of nari-adjectives. Most nari-adjectives became na-adjectives in Modern Japanese, while tari-adjectives either died out or survived as taru-adjective fossils, but a few nari adjectives followed a similar path to the tari-adjectives and became naru-adjective fossils. They are generally classed into attributives.

Attributives are few in number, and unlike the other words, are strictly limited to modifying nouns. Attributives never predicate sentences. They derive from other word classes, and so are not always given the same treatment syntactically. For example, ano (あの, "that") can be analysed as a noun or pronoun あ (a) plus the genitive ending の (no); aru (ある or 或る, "a certain"), saru (さる, "a certain"), and iwayuru (いわゆる, "so-called") can be analysed as verbs (iwayuru being an obsolete passive form of the verb iu (言う) "to speak"); and ōkina (大きな, "big") can be analysed as the one remaining form of the obsolete adjectival noun ōki nari. Attributive onaji (同じ, "the same") is sometimes considered to be an attributive, but it is usually analysed as simply an irregular adjectival verb (note that it has an adverbial form onajiku). The final form onaji, which occurs with the copula, is usually considered to be a noun, albeit one derived from the adjectival verb.

It can be seen that attributives are analysed variously as nouns, verbs, or adjectival nouns.

Various archaic forms from Middle Japanese remain as fossils, primarily uses of -shi (〜し) or -ki (〜き) forms that in Modern Japanese would usually be -i (〜い). Everyday examples notably include yoshi (良し, good, ok) and nashi (無し, nothing) – in modern grammar yoi (良い) and nai (無い), respectively. Similarly, furuki yoki (古き良き, good old (days etc.)) uses archaic forms of furui (古い, old) and yoi (良い, good).

i-adjectives have a basic inflection created by dropping the 〜い (-i) from the end and replacing it with the appropriate ending. na-adjectives are made more polite by the use of です (desu). です is added directly after the inflected plain form and has no syntactic function; its only purpose is to make the utterance more polite (see Honorific speech in Japanese).

いい (ii, "good") is a special case because it comes from the adjective 良い (yoi). In present tense, it is read as いい (ii), but since it derives from よい (yoi), all of its inflections supplete its forms instead. For example, 良いですね (ii desu ne, "[It] is good") becomes 良かったですね (yokatta desu ne, "[It] was good"). かっこいい (kakkoii, "cool") also fits the same category because it is a mash-up of 格好 (kakkō) and いい (ii).[6]

い (i)-adjectives like 安い (yasui, "cheap") have the い (i) changed to ければ (kereba) to change them to conditional form, e.g., 安ければ (yasukereba); 安くなければ (yasukunakereba).

i-adjectives have a full verb inflection paradigm created through contraction with the former copular verb あり (ari), consisting of six verb bases, that obeys the grammar surrounding verbs in Japanese. The usage of the full inflection is more limited in Modern Japanese and the majority of adjective usage in Japanese will be within the bounds of the basic inflection above. Auxiliary verbs are attached to some of the verb bases in order to convey information; only the terminal, attributive, and imperative bases are used on their own without auxiliary support.

The two irrealis stems, 〜かろ (karo) and 〜から (kara), are used for different purposes. The 〜かろ stem is used to create the volitional inflection by appending the volitional auxiliary 〜う (u), e.g. 暑かろう (atsukarō), while the 〜から stem is used for the formal negation auxiliary 〜ず (zu) and all other purposes which require the irrealis stem, e.g., 暑からず (atsukarazu).

The volitional form is generally used to convey supposition or presumption; there are also set phrases which utilize this form, a notable example being the volitional form of 良い (yoi), 良かろう (yokarō), a formal or archaic expression for "very well" or "it would be best to..." and the volitional form of 無い (nai), 無かろう (nakarō), a formal or archaic expression for "probably not so".

The imperative form is rarely used outside of set expressions; a common usage is once again with 良い (yoi), and its imperative form 良かれ (yokare), in idiomatic set expressions like 良かれと思う (yokare to omou, to wish for the best, to have good intentions) or 良かれ悪しかれ (yokare-ashikare, good or bad, for better or for worse, be it good or bad), also making use of the imperative form of 悪しい (ashii, (formerly the regular word for "bad", since replaced by 悪い (warui))). The imperative form of 無い (nai), 無かれ (nakare), is also used in archaic speech to indicate prohibition or a command not to do something or to indicate that one must not do something (also spelled 勿れ, 毋れ, 莫れ).

na-adjectives have a basic inflection created by dropping the 〜な (-na) and replacing it with the appropriate form of the verb だ (da), the copula. As with i-adjectives, na-adjectives are also made more polite by the use of です (desu). です is used in its role as the polite form of the copula, therefore replacing だ (the plain form of the copula) in the plain form of these adjectives.

な (na)-adjectives have なら (nara) added to them to change to conditional form, and just like all other ない (nai) form inflections, behave like an い (i)-adjective when in negative form, e.g., 簡単じゃなければ (kantan ja nakereba).

Because na-adjectives are simply suffixed with the copula だ, they, too, like i-adjectives, have a full verb inflection paradigm with six bases that obeys the grammar surrounding Japanese verbs.

Similarly to i-adjectives, out of the multiple irrealis stems, the 〜だろ (daro) irrealis stem is only used with the volitional auxiliary suffix 〜う (u), to form the volitional form suffixed with volitional copula 〜だろう (darō), used primarily to present a supposition or presumption. The 〜では (dewa) irrealis stem is not considered a true irrealis stem because it is simply the continuative stem plus the case particle は (wa), but is nevertheless suffixied with standard negation auxiliary 〜ない (nai) to form the negative form (see the basic inflection above). The 〜なら (nara) irrealis stem is used with the formal negation auxiliary 〜ず (zu) and all other uses of the irrealis stem.

The 〜なる (naru) attributive form exists as a fossil from the archaic ナリ活用 (nari katsuyō), or nari-conjugation, the precursor to the modern na-adjective. Generally only the 〜な (na) form is used for attribution, but the 〜なる (naru) form may be used to add a sense of stress, intensity, profundity, formality, or an imitation of archaic speech, such as 人類の偉大なる遺産 (jinrui no idai-naru isan, "the great legacy of humanity"), as compared to 人類の偉大な遺産 (jinrui no idai-na isan). It may also be seen in set phrases, like in 親愛なる (shin'ai-naru), used to open and address a letter to someone, much like English dear.

The 〜なる (naru) attributive form is also used in naru-adjectives, like 単なる (tan-naru) or 聖なる (sei-naru). In almost all cases, these are used exclusively as pre-noun attributives and cannot be used in any of the other standard forms of na-adjectives. In Modern Japanese, they only serve to modify nouns and cannot be used terminally nor even adverbially, as a contrast with the similar taru-adjectives. It is generally considered ungrammatical or unnatural to use other forms with naru-adjectives, even if technically syntactically correct.

taru-adjectives have much more limited usage in Modern Japanese and generally can only be used attributively with 〜たる (taru) or adverbially with 〜と (to). Generally, to express past or negative forms, additional other words or syntax are added to the sentence rather than using the full verb paradigm. However, nevertheless, taru-adjectives do have a full verb paradigm with six bases that obeys the grammar surrounding verbs in Japanese, which may be used in archaic or highly formal speech.

The terminal form 〜たり (tari) is almost never used. Generic words like 物 (mono), 事 (koto), 人 (hito), and 方 (kata) are used as fill-ins with the attributive form instead.

Both i-adjectives and na-adjectives can form adverbs. In the case of i-adjectives, い (i) changes to く (ku):

熱くなる (atsuku naru, "become hot")

and in the case of na-adjectives, な (na) changes to に (ni):

変になる (hen ni naru, "become strange")

There are also some words like たくさん (takusan) and 全然 (zenzen) that are adverbs in their root form:

全然分かりません (zenzen wakarimasen, "[I] absolutely not understand.")

In a few cases, a 〜に (ni) form of a word is common while a 〜な (na) form is rare or non-existent, as in 誠に (makoto-ni, "sincerely") – 誠 (makoto, "sincerity") is common, but ×誠な (*makoto-na, "sincere") is generally not used.