Synonyms for ironclad

Adjective

1. ironclad, brassbound, inflexible (vs. flexible)

usage: inflexibly entrenched and unchangeable; "brassbound traditions"; "brassbound party loyalists"; "an ironclad rule"

2. ironclad, unassailable, unshakable, watertight, bulletproof, incontestable (vs. contestable), incontestible

usage: without flaws or loopholes; "an ironclad contract"; "a watertight alibi"; "a bulletproof argument"