RichThesaurus
indomitable
vs
never-say-die
indomitable
adj
Incapable of being subdued, overcome, or vanquished.
never-say-die
adj
That does not give up in despair; indomitable.
How often have the words
indomitable
and
never-say-die
occurred in a corpus of books?
(source:
Google Ngram Viewer
)