Trembling with fear or apprehension; greatly alarmed. A literary/emphatic expression still used occasionally in writing.
彼は上司に呼び出され、戦々慄々として面談室に入った。
He was summoned by his boss and entered the interview room trembling with fear.
危険な任務を前にして隊員たちは戦々慄々の面持ちだった。
Faced with the dangerous mission, the team members had a look of fearful apprehension.
株価暴落の知らせに投資家は戦々慄々として市場の動向を見守った。
Hearing news of the stock crash, investors watched the market nervously and apprehensively.