There are several synonyms that can be used instead of "not endured" depending on the context. "Cannot bear" refers to an emotional response, whereas "unbearable" is more objective. "Unacceptable" is a common alternative that can also suggest defiance or resistance. "Intolerable" is similar but often implies physical discomfort, while "insufferable" is more subjective and often used to describe people. "Unendurable" is another option that suggests a long-term or ongoing challenge, while "impossible" simply states that the situation cannot be endured. Finally, "unjustifiable" can be used when referring to situations that are perceived as unfair or unreasonable.