坚不可摧 | jiān bù kě cuī | invulnerable, indestructible, impregnable | |
固若金汤 | gù ruò jīn tāng | secure as a city protected by a wall of metal and a moat of boiling water (idiom) / well fortified / invulnerable to attack | |
刀枪不入 | dāo qiāng bù rù | lit. impervious to sword or spear (idiom) / fig. invulnerable / untouchable / thick-skinned / impervious to criticism |