Translation guide
The English word "undying" is used to describe something that never ends or fades, such as love, loyalty, or fame. In Japanese, this concept is expressed through adjectives, verbs, and set phrases that emphasize permanence, immortality, or an unbreakable nature. The most natural choice depends on what is being described and the nuance of "never dying" versus "eternal."
Describing abstract things like love, loyalty, or fame that never fade or end.
Literally 'indestructible' or 'immortal.' Commonly used for abstract concepts like love, soul, or fame that will never perish. Natural in both spoken and written Japanese.
Means 'eternal.' Very common for love, friendship, etc. Slightly more poetic than 不滅. Often used in songs and literature.
to vow undying love
Literally 'does not decay.' Used for things that remain fresh or unfading, like memories or beauty. More literary.
undying memories
Describing living things or mythical beings that cannot die.
Describing physical or metaphorical things that never fade or go out.
不滅 (fumetsu) emphasizes indestructibility and is often used for abstract concepts like love or fame. 永遠 (eien) means 'eternal' and is more about endless time, commonly used in romantic contexts. 不死 (fushi) specifically means 'not dying' and is used for immortal beings. Choose based on whether you want to stress permanence, timelessness, or literal immortality.
Avoid directly translating 'undying' as 死なない (shinanai, 'not dying') for abstract concepts. It sounds unnatural and overly literal. Use 不滅 or 永遠 instead.