Translation guide
The English phrase 'be dull' can describe a lack of sharpness (literal or figurative), a lack of excitement, or a lack of intelligence. This guide organizes Japanese expressions by these core meanings, from most common to niche.
Describing a blade, tool, or point that has lost its sharpness.
The most common adjective for 'dull' in the sense of not sharp. Can also be used figuratively for slow-witted or sluggish.
Literally 'the cutting quality is bad'. A natural way to say something doesn't cut well, implying dullness.
This knife is dull (doesn't cut well).
A somewhat old-fashioned or colloquial term for a dull blade, often implying it's useless. Can also mean a lazy person.
This sword is dull.
Describing an event, person, or thing that lacks excitement or interest.
The standard adjective for 'boring' or 'dull'. Used for things that fail to hold interest.
The movie was dull.
His stories are dull.
Very common word for 'boring', 'dull', or 'uninteresting'. Slightly more casual than 退屈.
Literally 'lacks interestingness'. A more analytical way to say something is dull.
His lecture was dull (lacked interest).
Means 'plain', 'simple', or 'subdued'. Can imply dullness in the sense of lacking flashiness or excitement.
Her clothes are dull (plain).
Describing a person who is not sharp mentally.
The same word as for physical dullness, also commonly used for mental slowness or lack of quick understanding.
He is slow on the uptake (literally: his mental rotation is dull).
I'm dull with numbers.
A stronger, more formal word meaning 'stupid' or 'dull-witted'. Often used in writing.
He is a dull-witted man.
A colloquial and slightly derogatory term for a slow or dull person, both mentally and physically.
Describing a surface, color, or light that is not bright or shiny.
Describes colors or surfaces that are dull, faded, or lacking brightness. Often used for paint, metal, or complexion.
a wall of a dull color
The metal is dull (tarnished).
Literally 'lacks luster'. Used for surfaces that should be shiny but aren't.
This table is dull (has no shine).
Means 'cloudy' or 'foggy', but can describe a dull, hazy surface like a mirror or glass.
a dull mirror (fogged up)
Describing a dull ache or throbbing pain rather than a sharp one.
Describing a dull, gray, sunless day or mood.
Describes a dull, overcast sky or a heavy, gloomy atmosphere. Very common for weather.
The weather is dull today.
Simply means 'cloudy', but can imply a dull, gray sky.
a dull (cloudy) sky
鈍い (nibui) is for physical dullness (blades, senses, mind). 退屈 (taikutsu) and つまらない (tsumaranai) are for boredom. 退屈 is slightly more formal, つまらない is more casual and can also mean 'trivial' or 'worthless'.
This knife is dull.
This movie is dull (boring).
This game is dull (boring).
While 鈍い can mean 'slow-witted', it is not used to describe an uninteresting event. Use 退屈 or つまらない for that meaning.
This book is dull.
That guy is dull/slow.