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.
The kitchen knife has become dull.
Phrase meaning 'sharpness becomes bad', a natural alternative.
This knife has become dull.
Describing senses, pain, or emotions that become less sharp or intense.
Describing something that loses excitement or interest.
Standard way to say 'become boring/dull'.
This game quickly became dull.
Means 'become tedious/boring', often for situations or activities.
The lecture became dull.
Means 'become stuck in a rut/routine', often for relationships or creative work.
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.
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.
The silverware has become dull.
Describing business, economy, or activity losing momentum.
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.