faithful and unyielding; loyal and firm in one's principles or integrity; unswerving to the end

Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings

(bound form) to change or alter, used specifically for attitudes or feelings; often found in phrases describing unyielding loyalty such as 至死不渝 zhì​sǐ​bù​yú