- ironclad, unassailable, unshakable, watertight, bulletproof - without flaws or loopholes; "an ironclad contract"; "a watertight alibi"; "a bulletproof argument"
Antonym: contestable (indirect, via incontestable)
- bulletproof - not penetrable by bullets; "bulletproof glass"; "bulletproof vest"
Antonyms: unarmored, unarmoured (indirect, via armored)