"indefensible" in the adjective sense
1. indefensible, untenable
of theories etc) incapable of being defended or justified
2. indefensible
not able to be protected against attack
3. indefensible, insupportable, unjustifiable, unwarrantable, unwarranted
incapable of being justified or explained
Source: WordNet® (An amazing lexical database of English)
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