ironclad
adjective /ˈaɪənklæd/
/ˈaɪərnklæd/
- so strong that it cannot be challenged or changed
- an ironclad alibi/contract/excuse/guarantee
- His memo is ironclad proof he was involved.
Oxford Collocations DictionaryIronclad is used with these nouns:- alibi
- guarantee
- warship
- …