unquestionable

adjective

1. not open to question; beyond doubt or dispute; indisputable; undeniable; certain: an unquestionable fact.
2. above criticism; unexceptionable: a man of unquestionable principles.

adjective

1. indubitable or indisputable
2. not admitting of exception or qualificationan unquestionable decision

adj.c.1600, from un- (1) “not” + questionable. Related: Unquestionably.