金城汤池 jīnchéngtāngchí impregnable fortress Origin Definitions Defs Strokes Stroke Words Sentences Sents 金城 jīnchéng impregnable city an extremely strong or fortified city; literally a city of metal汤池 湯池 tāngchí impenetrable moat (literary) A moat filled with boiling water, used as a metaphor for an extremely strong and impenetrable defense; often used in the idiom 金城汤池 jīnchéngtāngchí