WordWeb Online

1. Having an unobvious or mysterious meaning; hard to understand
   "prophetic texts so enigmatic that their meaning has been disputed for centuries"; "I didn't grasp the meaning of that enigmatic comment until much later";
   - enigmatical, puzzling
    
2. Resembling an oracle in obscurity of thought
   "so enigmatic that priests might have to clarify it"; "an enigmatic smile";
   - oracular

See also: ambiguous, incomprehensible, uncomprehensible

Encyclopedia: Enigmatic