前代未聞 (zendaimimon) Japanese meaning: unprecedented | Kotomoraこれは前代未聞の大災害だ。
This is an unprecedented catastrophe.
They achieved a record-breaking feat.
Usage patterns
前代未聞の〈事〉an unprecedented ~ (event, incident, etc.)
The unprecedented incident caused a stir throughout society.
前代未聞の〈事〉が起こるan unheard-of ~ occurs
An unheard-of event occurred in that village.
