Isolated and without assistance; alone and unassisted (having no support or allies).
彼は会議で意見が受け入れられず、孤立無援の立場に追い込まれた。
His opinion wasn't accepted at the meeting, and he was driven into an isolated, unsupported position.
豪雨で道路が寸断され、村は一時孤立無援となった。
Roads were cut off by heavy rain, and the village was temporarily isolated and without aid.
外交問題で国は孤立無援に陥り、外部からの支援を求めた。
The country fell into diplomatic isolation without allies and sought external support.