Pronunciation: (u-nig'mu),[key] —n., —pl.-mas, -ma•taPronunciation: (-mu-tu).[key] 1. 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. (cap.) 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.