Inexcusable is a synonym of unbearable.
As adjectives the difference between inexcusable and unbearable
is that inexcusable is not excusable while unbearable is so unpleasant or painful as to be unendurable.
unbearable
English
Adjective
(
en adjective)
so unpleasant or painful as to be unendurable
Synonyms
* insufferable
* unsupportable