[法] 无可反驳的, 无懈可击的

1. immune to attack; incapable of being tampered with

<adj.all>
an impregnable fortress
fortifications that made the frontier inviolable
a secure telephone connection

2. impossible to assail

<adj.all>

3. without flaws or loopholes

<adj.all>
an ironclad contract
a watertight alibi
a bulletproof argument