untenably
/ʌnˈtɛnəbli/Definitions
1. adverb
in a manner that cannot be defended or justified; indefensibly
“The company’s decision was untenably expensive and resulted in significant financial losses.”
2. adverb
in a way that cannot be supported or maintained; impractically
“The current economic situation makes it untenably difficult for low-income families to afford housing.”