taru-adjective, adverb taking the 'to' particle
disappointed; dejected; dumbfounded
Describes a state of visible disappointment or dejection, often with a stunned or blank expression. Used in literary or formal contexts.
彼は結果を聞いて憮然とした表情を浮かべた。
He wore a disappointed expression upon hearing the result.
憮然として立ち尽くす姿が印象的だった。
The sight of him standing there dejected was striking.
taru-adjective, adverb taking the 'to' particle
A less common, somewhat dated sense expressing indignation or anger. Often overlaps with the disappointed sense in modern usage.
不当な扱いに彼は憮然として抗議した。
Indignant at the unfair treatment, he protested.
憮 (disappointed, bewildered) + 然 (state, manner). A Sino-Japanese word used in classical and literary Japanese to describe a state of dejection or indignation.