enigma
noun
[ ɪˈnɪɡmə ]
• a person or thing that is mysterious or difficult to understand.
• "Madeleine was still an enigma to him"
Similar:
mystery,
puzzle,
riddle,
conundrum,
paradox,
problem,
unsolved problem,
question,
question mark,
quandary,
a closed book,
poser,
teaser,
brain-teaser,
stumper,
Origin:
mid 16th century: via Latin from Greek ainigma, from ainissesthai ‘speak allusively’, from ainos ‘fable’.
