a puzzling or inexplicable occurrence or situation: His disappearance is an enigma that has given rise to much speculation.
2.
a person of puzzling or contradictory character: To me he has always been an enigma, one minute completely insensitive, the next moved to tears.
3.
a saying, question, picture, etc., containing a hidden meaning; riddle.
4.
( initial capital letter ) a German-built enciphering machine developed for commercial use in the early 1920s and later adapted and appropriated by German and other Axis powers for military use through World War II.
Origin: 1530–40; < Latinaenigma < Greekaínigma, equivalent to ainik- (stem of ainíssesthai to speak in riddles, derivative of aînos fable) + -ma noun suffix of result
mid-15c., from L. aenigma "riddle," from Gk. ainigma, from ainissesthai "speak obscurely, speak in riddles," from ainos "fable, riddle," of unknown origin.
hardware, cryptography The electro-mechanical cipher engine used by the Germans in World War II. Many of their messages were deciphered at Bletchley Park, by Alan Turing and others. (2000-09-30)