untenable
adj.impossible to defend or continue because of a serious problem or mistake. You use this to describe a situation, like a job or an argument, that cannot last any longer.
adj.incapable of being defended, maintained, or occupied against attack or criticism. Often describes positions, arguments, or professional situations that have become impossible to sustain.
“His position at the company became untenable after the scandal.”
“The senator's argument was rendered untenable when new evidence proved his initial assumptions were entirely false.”
“As the structural integrity of the building continued to fail, the residents found themselves in an untenable living situation that required immediate evacuation by the local authorities.”
Commonly follows a linking verb like 'become', 'remain', or 'render'.
“Henderson called the opt-out register “a very significant initiative”, claiming it was “untenable” that people would be expected to individually opt out of ads on each website, streaming service and social media platform.”
“The latest proposed US levy has stoked concern about financial devastation and untenable export costs among Canadian business owners, the CBC reported.”
From un- + tenable.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.