enigma

1. Something or someone puzzling, mysterious or inexplicable. (countable, uncountable)
2. A riddle, or a difficult problem. (countable, uncountable)
3. Riddles and puzzles, collectively. (countable, uncountable)
4. Mysteriousness; obscurity; a lack of clarity. (countable, uncountable)
5. A style of literature characterized by obscurity and hints of transcendental meaning. (countable, uncountable)
6. A protein with three LIM domains (a conserved cysteine- and histidine-rich structure of two adjacent zinc fingers) at the C terminus that regulates protein phosphorylation. (countable, uncountable)
7. The Talaud kingfisher, Todiramphus enigma. (countable, uncountable)
8. Any member of the species Oedaleonotus enigma of grasshoppers. (countable, uncountable)

Plural enigmas