unpredictable
un- + predictable
https://gyazo.com/8cbfd8231781efe62e97616af461b8c9
source: What I think of when a girl says they're "unpredictable" - GIF on Imgur
adjective
not able to be predicted:
予測［予言］できない
e.g. the unpredictable weather of the Scottish islands.
(of a person) behaving in a way that is not easily predicted:
〈人が〉行動の読めない, 気まぐれな; 変わりやすい.
e.g. he is emotional and unpredictable.