Undetermined
Part of speech: adjective
Definition: Not determined; not settled; not decided. Not limited; not defined; indeterminate.
Unexplained
Part of speech: adjective
Definition: Not explained. Of unknown cause or origin.
Example sentence: We will never fully explain the world by appealing to something outside it that must simply be accepted on faith, be it an unexplained God or an unexplained set of mathematical laws.