にぶ
nibui

i-Adjective

1. dull (e.g. a knife); blunt

たしかに かれ少々 しょうしょうにぶいが勤勉 きんべんだ。
tashikani karewa shōshō nibuiga kimbenda.
Indeed he may be a little dull, but he is diligent.
i-Adjective

2. thickheaded; obtuse; stupid

i-Adjective

3. dull (sound, color, etc.); dim (light)

i-Adjective

4. slow; sluggish; inert; lethargic

i-Adjective

5. insensitive; dull (e.g. reflexes); unperceptive; unfeeling