incomprehensible
🇺🇸
/ɪnˌkɑːmprɪˈhensəbl/
🇬🇧
/ɪnˌkɒmprɪˈhensəbl/
Unable to be understood or too complex to grasp.
The professor's lecture was so full of technical jargon that it was incomprehensible to the students.