in ‧ dom ‧ i ‧ ta ‧ ble /ɪnˈdɒmətəb ə l, ɪnˈdɒmɪtəb ə l $ ɪnˈdɑː-/ BrE AmE adjective formal
[ Date: 1600-1700 ; Language: Late Latin ; Origin: indomitabilis , from Latin domitare 'to control the behavior of' ]
having great determination or courage:
an indomitable old lady
indomitable spirit/will/courage etc
Alice was a woman of indomitable spirit.