Unsupportable
Part of speech: adjective
Definition: Not able to be supported or endured.
Intolerable
Part of speech: adjective
Definition: Not tolerable; not capable of being borne or endured; not proper or right to be allowed; insufferable; insupportable; unbearable.Extremely offensive or insulting.
Example sentence: To be a programmer is to develop a carefully managed relationship with error. There's no getting around it. You either make your accommodations with failure, or the work will become intolerable.