Free from doubt; certain

ETYM Pref. in- not + disputable: cf. French indisputable.
Impossible to doubt or dispute; SYN. sure.

ETYM Latin indubitabilis: cf. French indubitable. Related to In- not, and Dubitable.
Not dubitable or doubtful; too evident to admit of doubt; unquestionable; evident; apparently certain.

1. Infallible or unfailing
2. Certain not to fail
3. Physically secure or dependable
4. (Of persons) Worthy of trust or confidence; SYN. trusted.

Not possible to deny.

Not doubted; genuine, undisputed

Admitting of no doubt or misunderstanding; having only one meaning or interpretation and leading to only one conclusion; SYN. univocal, unambiguous.

Clearly evident to the mind