ない (rōmaji -nai)
- used to form derivative -i adjectives from other terms: having that quality, having that state; very much that quality or state
- setsunai, itokenai, gikochinai
- very moving, really young of manner, having clumsiness
ない (-i inflection, rōmaji nai)
- 無い: not, there is no, lack
- Supūn ga nai.
- There is no spoon.
- (by extension) 亡い: passed away, dead
- This term is often spelled in hiragana.
- In public speech and written language, the irregular expressions ありません (arimasen) and ありませんでした (arimasen deshita) (past) are recommended instead of ないです (nai desu) and なかったです (nakatta desu).
- When used as an auxiliary adjective, follows the 連用形 (ren'yōkei, “continuative or stem form”) of -i adjectives ending in く (-ku), and the 連用形 (ren'yōkei, “continuative or stem form”) of -na adjectives and nominals ending in で (de). In either case a binding particle (係助詞) can be inserted between the ren'yōkei and the nai, but は (wa) is usually used for the latter. では (de wa) can be contracted to じゃ (ja)
- Kono pasokon wa yasuku nai.
- This computer is not cheap.
- Watashi wa kankokugo wa jōzu de wa arimasen.
- I am not good at Korean.
First appears in texts from the late Muromachi period as an eastern-dialect term. Sometimes described as related to ancient eastern-dialect negative ending なふ (nafu), but there is a sizable gap of time between the apparent disappearance of nafu and the emergence of nai. Moreover, nafu conjugated as a verb, whereas nai conjugates as an adjective.
That said, both nafu and nai probably derive ultimately from ancient copula or stative verb ぬ (nu), with the negative sense possibly originating from the 未然形 (mizenkei, “irrealis or incomplete form”) of the verb stem, to which these endings attach.
The nai auxiliary conjugates as a regular -i adjective just like the adjective nai in modern Japanese, but the patterns for the auxiliary were originally different from the adjective. In the Edo period, the auxiliary conjugated irregularly, including nanda instead of modern nakatta (past), and naikereba instead of modern nakereba (conditional).
ない (rōmaji -nai)
- (jodōshi) Used to form the negative of verbs: not, don't
- Gakkō ni ikanai.
- I don't go to school.
- Attaches to the 未然形 (mizenkei, “incomplete form”) of the verb. For 五段活用 (godan katsuyō, “quintigrade conjugation”, also known in English as “type 1”) verbs, this is the stem form ending in -a.
- Generally, ません (masen) and ませんでした (masen deshita) (past) are the recommended formal negative endings, instead of the somewhat less formal ないです (nai desu) and なかったです (nakatta desu).
- The auxiliary nai and the adjective 無い (nai) have mostly converged in modern usage. One distinction that is still maintained by some speakers appears when attaching そう (sō, “appears like, seems like”) or すぎる (sugiru, “too, too much, in excess”):