incontestable (adj) – indisputable or incontrovertible; cannot be contested
BREAKDOWN: IN- (not) + CON- (with) + TEST- (witness)+ -ABLE (able to be)
— to contest means to compete or contend; to dispute, oppose, or argue against
— a contest is also a competition, struggle, or strife
This word is built on the root TEST-, which means witness.
Common TEST- words include contest, detest, and protest.
More esoteric TEST- words include intestacy and obtest.