甚だ is a formal, literary intensifier. It is common in official statements, formal letters, and written Japanese.
Common collocations
- 甚だ遺憾: deeply regrettable (very formal)
- 甚だしい: extreme, excessive (adjective form)
- 甚だ失礼: terribly rude
- 甚だ不本意: much against one's wishes
Similar words
- とても: very (neutral, everyday)
- 非常に: extremely (formal but common)
- 極めて: extremely (formal); 甚だ is stiffer still and mostly modifies negative words (遺憾, 失礼, 迷惑)