IPA: /ˌʌn.kəmˈprɒm.ɪ.zə.bəl/
KK: /ʌnˌkɑmprəˈmaɪzəbl/
Something that cannot be changed or agreed upon; it remains firm and unyielding.
Her uncompromisable stance on the issue made negotiations very difficult.
Uncompromisable → It is formed from "un-" (meaning not), "compromise" (from Latin "compromissum", meaning a mutual promise or agreement), and "-able" (meaning capable of). The word means not capable of being agreed upon or settled through compromise.
Think of 'not' ('un-') being able to reach a 'mutual agreement' ('compromise') — that's why uncompromisable means something that cannot be settled.