slowness; inertness; dullness
Describes a person's slow or unresponsive nature, often used in self-deprecating or formal contexts. More common in written or literary Japanese.
不敏を恥じるばかりです。
I am only ashamed of my own slowness.
inability; lack of talent; stupidity
Refers to a lack of ability or talent, sometimes implying stupidity. Also used in self-deprecating or formal expressions.
I caused you trouble due to my own inability.
The word is composed of 不 (not) and 敏 (quick, clever). The exact historical derivation is uncertain, but it follows a common Sino-Japanese pattern of negating a positive quality.