adj.堅(jiān)不可摧的；不可戰(zhàn)勝的

They will establish impregnable fortresses. 他們將建造堅(jiān)不可摧的城堡。

The lofty walls of the castle seemed impregnable. 這座城堡的高墻似乎堅(jiān)不可摧。

The lawyer won his case with an impregnable argument. 律師以無(wú)可辯駁的論據(jù)打贏了那場(chǎng)官司。