inopinable
/ˌɪnəˈpɪnəbəl/Definitions
1. adjective
Impossible to anticipate or forecast; unpredictable.
“The outcome of the election was inopinable, keeping everyone on the edge of their seats.”
2. noun
Something that is impossible to anticipate or forecast.
“The weather was an inopinable force that ruined the outdoor wedding plans.”