통탄해요 · 통탄했어요 · 통탄할 거예요 · 통탄하세요
to deeply lament, to bitterly deplore
Example
국민들은 어이없는 사고로 아이들을 잃은 것을 통탄했습니다.
The nation bitterly mourned losing children in such a senseless accident.
Word parts
통 painful+탄 sigh
Literally 'painful sigh' — the strongest of the 'sigh' verbs.