closed book closed-angle glaucoma • closed-captioned · · · Info · Definitions · Synonyms · Characters · · closed book · · Text Common · · Latin · · Scripts 11 · · Length 2 · · Syllables Definitions · · · (noun) something that baffles understanding and cannot be explained. Synonyms: mystery, enigma, secret, closed book. Examples: "How it got out is a mystery." "It remains one of nature's secrets." · · Noun Definition 1 Synonyms · · · mystery · · Synonym 1 enigma · · Synonym 2 secret · · Synonym 3 Characters · · space U+0020 b latin small letter b U+0062 c latin small letter c U+0063 d latin small letter d U+0064 e latin small letter e U+0065 k latin small letter k U+006B l latin small letter l U+006C o latin small letter o U+006F s latin small letter s U+0073