Definition of unriddleable in English:
unriddleable
(also unriddlable)
adjective (ˌ)ʌnˈrɪd(ə)ləbl(ˌ)ʌnˈrɪdləbl
Of a mystery, etc.: unsolvable.
Origin
Mid 17th century; earliest use found in John Evelyn (1620–1706), diarist and writer. From un- + riddle + -able.