not clear or capable of being understood; incognizable

agnosticism; the philosophical view that the nature of the universe or the existence of the divine is unknown or unknowable

the philosophical doctrine that the world is knowable (opposite of agnosticism)

It is also not certain; perhaps or maybe; used to indicate that a particular outcome or reason cannot be fully predicted or ruled out

a person who believes that nothing is known or can be known of the existence or nature of God or of anything beyond material phenomena

knowability; the quality of being knowable or understandable