unimpeachable

unimpeachable /ˌʌnɪmˈpiːtʃəbəl/ adjective
unimpeachable
/ˌʌnɪmˈpiːtʃəbəl/
adjective
Britannica Dictionary definition of UNIMPEACHABLE
formal
: very reliable and trusted : not able to be doubted or questioned

— unimpeachably

/ˌʌnɪmˈpiːtʃəbli/ adverb