unassailable
adjectiveUK /ˌʌnəˈseɪləbl/
US /ˌʌnəˈseɪləbl/
So strong that nobody can beat it or argue against it.
Her argument was so clear and well-supported that it was unassailable.
RELATED WORDS
OTHER MEANINGS
2. Impossible to attack or capture by force.
The castle sat on a high cliff, making it unassailable.
3. Impossible to question or doubt because it is clearly true.
His record of honesty was unassailable.
4. Not able to be criticized successfully.
The team's lead in the final minutes was unassailable.