unpredictable unpredictable /ˌənprɪˈdɪktəbəl/

adjective

1. () Not capable of being foretold  ( unpredictable )
   not capable of being foretold
   
2. Not occurring at a regular rate or fixed intervals  ( unpredictable , irregular )
   not occurring at a regular rate or fixed intervals
    An irregular heartbeat
   an irregular heartbeat
   
3. Unknown in advance  ( unpredictable )
   unknown in advance
    An unpredictable (or indeterminable) future
   an unpredictable (or indeterminable) future