regrettable matter; unfortunate affair
A literary or formal noun referring to something that causes regret or resentment. Not used in everyday conversation; more common in written or elevated contexts.
His death is truly a regrettable matter.
Compound of 恨 (こん, 'resentment, regret') and 事 (じ, 'matter, affair'). The exact historical derivation is uncertain, but the word is conventionally associated with a formal expression of regret.