ないし（は）

• Reading: ないし
• Romaji: naishi
• Formation: A ないし（は） B
• Kanji breakdown: 乃 (の/ない) = from, of; 至 (し/いた・る) = to reach, to arrive at

Meaning

A particle meaning 'or,' 'to,' or 'through,' used to present two possible choices or to indicate a range between a minimum and maximum. It appears primarily in formal and legal contexts.

ないし（は） has two distinct uses: presenting alternatives ('or, either...or') and indicating a range ('from...to, between...and'). In its alternative use, it functions similarly to または or あるいは but is more formal and often found in legal and official texts. In its range use, it specifies the lower and upper bounds — for example, 三日ないし五日 means 'three to five days.' The は after ないし is optional and adds slight emphasis. It is derived from classical Japanese and retains a literary, formal tone. In modern usage, it appears in contracts, regulations, academic writing, and formal announcements. It is rarely used in casual conversation, where から～まで or か would be preferred.

Examples

1. 工事期間は三か月ないし六か月を見込んでいる。 The construction period is expected to be three to six months.
2. 参加費は五千円ないし一万円の範囲で設定される予定だ。 The participation fee is planned to be set in the range of five thousand to ten thousand yen.
3. 違反者には警告ないし処分が科される。 Violators will be subject to a warning or disciplinary action.

Usage Guide

Context: written, legal, academic

Tone: official

Do Say

• 審査には一か月ないし二か月を要する。
• 本条項の違反には罰金ないし資格停止の処分が適用される。
• 出席者は五十名ないし七十名になる見込みだ。

Don't Say

• 今日ないし明日、遊びに行こう。(Using ないし in casual conversation — too formal and stiff) → 今日か明日、遊びに行こう。
• りんごないしみかんを食べた。(Using ないし for a trivial everyday choice — unnaturally formal) → りんごかみかんを食べた。

Origin & History

ないし derives from the classical Japanese expression 乃至, which was borrowed from Chinese legal and Buddhist terminology meaning 'from...to' or 'up to and including.' It has been used in Japanese legal writing since the medieval period.

Cultural Context

Generation: All ages

Social background: Universal