unfathomable
Pronunciation:
/ʌnˈfæðməbəl/adjective
Definitions
Impossible to fathom or understand.
Example: The sheer numbers they attacked with were unfathomable.
Synonyms:fathomlessincomprehensibleunintelligibleAntonyms:explicableintelligibleDifficult to penetrate.
Synonyms:impenetrableimpregnableAntonyms:penetrablepregnable