na-adjective, noun
dullness; slowness of mind; stupidity
Literary or formal term for mental slowness or dullness; not used in everyday conversation. Often implies a lack of sharpness or wit.
彼の遅鈍な反応にいらだちを覚えた。
I felt irritated by his dull-witted response.
遅鈍な頭脳ではこの問題は解けない。
A slow mind cannot solve this problem.