unobtainable

unobtainable /ˌʌnəbˈteɪnəbəl/ adjective
unobtainable
/ˌʌnəbˈteɪnəbəl/
adjective
Britannica Dictionary definition of UNOBTAINABLE
[more unobtainable; most unobtainable]
: not possible to get or achieve