ぬ・
ぬ and ざる are literary negative verb endings roughly equivalent to the ordinary modern negative ない. The first can finish a clause or modify a noun, while the second appears chiefly before a noun or in established written patterns.
Choosing between the two forms
ぬ can serve as the negative ending of a clause and can also appear before a noun. ざる is especially associated with a following noun and established written patterns. Although both carry negative meaning, do not treat ざる as a freely interchangeable sentence-final alternative to ぬ.
Core patterns
その真意は、今となっては誰にも分からぬ。
Now, no one can know the true intention behind it.
Analyze分からぬ finishes the clause. The wording has a literary, reflective tone.
これは、まだ世に知られざる事実である。
This is a fact that is not yet known to the world.
Analyze知られざる directly modifies the following noun, a characteristic written use of ざる.
十分な検討をせぬまま、結論を急ぐべきではない。
One should not rush to a conclusion without sufficient consideration.
Analyzeせぬ shows the irregular negative base of the verb meaning “to do.”
The ordinary modern negative
ない remains the normal choice in everyday modern Japanese. Literary ぬ and ざる express negative meaning but also add a marked written, old-fashioned, proverbial, or fixed-expression flavor.
More examples
彼は何食わぬ顔で会議を続けた。
He continued the meeting as if nothing had happened.
Analyze何食わぬ顔 is an established expression for acting completely unconcerned or innocent.
予期せぬ停電で、作業は中断した。
An unexpected power outage interrupted the work.
Analyzeその島には、いまだ解明されざる遺跡が残る。
Ruins that have yet to be explained remain on the island.
Analyze来るはずの使者が、夜になっても来ぬ。
The envoy who was due to arrive had still not come by nightfall.
Analyze来ぬ uses the irregular reading and gives the sentence a literary narrative tone.