いけない

• Reading: いけない
• Romaji: ikenai
• Pronunciation: /i.ke.na.i/

Meaning

Must not; should not; bad; wrong. Expresses prohibition or that something is unacceptable.

An i-adjective derived from the potential negative of 行く (iku, to go). Most commonly appears in the grammar pattern ～てはいけない (must not do). Also used as a standalone exclamation meaning 'Oh no!' when realising a mistake. Interchangeable with いけません in polite speech.

Examples

1. ここでタバコを吸ってはいけない。 You must not smoke here.
2. いけない、財布を忘れてきた。 Oh no, I forgot my wallet!
3. 夜遅くまで起きていてはいけないよ。 You shouldn't stay up late at night.

Usage Guide

Context: rules, parenting, self-correction

Tone: cautionary

Origin & History

Negative form of いける (to be able to go/proceed), which itself derives from 行ける. The underlying meaning is 'cannot proceed' or 'it won't do,' extended to express prohibition or disapproval.

Cultural Context

Era: Edo

Generation: All ages

Social background: Universal