na-adjective, noun
presumptuous; audacious; forward
Used in formal or self-deprecating contexts when one is about to say or do something that might be seen as overstepping one's position. Often appears in the set phrase 僭越ながら (with all due respect / if I may be so bold).
See also: 僭越ながら
僭越ながら、一言申し上げます。
If I may be so bold, I would like to say a word.
僭越な態
His presumptuous attitude incurred his boss's displeasure.
From Chinese 僭越 (jiànyuè), meaning to overstep one's authority. The kanji 僭 means 'usurp' or 'overstep', and 越 means 'exceed' or 'go beyond'.