gù​ruò​jīn​tāng

impregnable

  1. adjective
    solid
    (bound form) solid; firm; strong; secure; hard (not liquid or gaseous)
  2. ruò adjectiveadverb
    to seem
    to seem; to appear to; to be like; to look as if
  3. impregnable fortress
    (literary) an impregnable fortress; specifically used to describe defenses that are extremely solid and secure; abbreviation for 金城汤池 jīn​chéng​tāng​chí