Translation guide
How to express that something loses sharpness, intensity, interest, or brightness in Japanese.
Describing a blade or cutting edge that is no longer sharp.
Intransitive verb meaning 'to become dull/blunt'. Used for blades, senses, skills, etc.
包丁が鈍った。
The kitchen knife has become dull.
Phrase meaning 'sharpness becomes bad', a natural alternative.
このナイフは切れ味が悪くなった。
This knife has become dull.
Describing senses, pain, or emotions that become less sharp or intense.
Also used for senses and feelings becoming dull.
年をとると感覚が鈍る。
As you get older, your senses become dull.
痛みが鈍ってきた。
The pain has become dull.
Means 'to fade/thin out', used for feelings, memories, consciousness.
Describing something that loses excitement or interest.
Standard way to say 'become boring/dull'.
このゲームはすぐにつまらなくなった。
This game quickly became dull.
Means 'become tedious/boring', often for situations or activities.
講義が退屈になった。
The lecture became dull.
Means 'become stuck in a rut/routine', often for relationships or creative work.
付き合いがマンネリ化してきた。
Our relationship has become dull.
Describing colors, metals, or surfaces that become less bright or shiny.
Intransitive verb meaning 'to become dull/dim/sober' in color or luster.
色がくすんでしまった。
The color has become dull.
Means 'to become cloudy/dim', used for mirrors, glass, metal surfaces losing shine.
Literally 'luster disappears', more formal or descriptive.
銀食器の光沢がなくなった。
The silverware has become dull.
Describing business, economy, or activity losing momentum.
Formal term meaning 'to slow down/become sluggish', common in news.
経済成長が鈍化している。
Economic growth has become dull.
Means 'to stagnate', used for markets, progress, etc.
売り上げが停滞している。
Sales have become dull.
鈍る is for sharpness, senses, skills; くすむ is for colors and luster. Do not use 鈍る for colors.
Avoid directly translating 'become dull' as 鈍くなる in all contexts. Use the specific verbs above for natural Japanese.
恐怖心が薄れた。
The feeling of fear became dull.
The mirror has become dull and hard to see.