1.
rude; impolite; ill-mannered
Lacking proper manners or etiquette, behaving in an inappropriate way.
2.
blunt; abrupt; forward
Being direct or forward in a way that disregards social conventions.
Etymology
不 (not) + 躾 (discipline, training in manners) - literally "lacking discipline/training"
Common patterns
- 不躾ながら〜 - polite preface meaning "I know this is forward, but..."
- 不躾な質問 - impolite/forward question
- 不躾なお願い - presumptuous request
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Often used in formal contexts as a self-deprecating acknowledgment before asking something potentially inappropriate or personal.