in ‧ con ‧ tro ‧ ver ‧ ti ‧ ble /ɪnˌkɒntrəˈvɜːtəb ə l, ɪnˌkɒntrəˈvɜːtɪb ə l $ ɪnˌkɑːntrəˈvɜːr-/ BrE AmE adjective
[ Date: 1600-1700 ; Origin: controvertible 'that can be argued about' (17-21 centuries) , from controvert 'to dispute' (17-21 centuries) , from controversy ]
definitely true and impossible to be proved false SYN indisputable :
CCTV provided incontrovertible evidence that he was at the scene of the crime.
—incontrovertibly adverb