Incomprehensible is a word that expresses the idea of something that is difficult or impossible to understand. There are several synonyms for this word that can be used to convey the same meaning. One such synonym is unfathomable which means something that cannot be fully understood or explored. Obscure is another word that can be used to describe something that is difficult to understand. Other synonyms for incomprehensible include mysterious, unintelligible, and inscrutable. Each of these words conveys a sense of something that is beyond comprehension or understanding, and can be used interchangeably with incomprehensible to describe difficult concepts or ideas.