closed booknoun [ S ]
uk/ˌkləʊzd ˈbʊk/us/ˌkloʊzd ˈbʊk/informala subject about which you know or understand nothing:
I'm afraid physics will always be a closed book to me.
Thesaurus: synonyms and related words
Difficult to understand
- (as) clear as mud idiom
- abstruse
- ambiguity
- ambiguous
- arcane
- blurred
- diffuse
- esoteric
- fathomless
- garble
- get it into your thick head idiom
- impalpable
- obscure
- opaque
- over your head idiom
- paradox
- puzzler
- puzzling
- recherché
- veiled
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