IPA: //ʌnˈdaɪ.ɪŋ//
KK: /ʌnˈdaɪɪŋ/
Something that lasts forever or never ends; it cannot die or fade away.
She has an undying love for her family.
Undying is formed from "un-" (meaning not) and "dying" (from Old English "dīgan", meaning to die). The word describes something that does not die or is eternal.
Think of 'not' ('un-') dying, which helps you remember that 'undying' means something that is eternal or never dies.