indefinitely; for a long time; forever
Emphatic form of いつまでも, stressing that something continues without end or for an extremely long time. Often used in wishes, promises, or complaints about something that never changes.
I will never forget you, no matter how much time passes.
May this happiness last forever.
Kanji spelling using 何時 for いつ; very rare and mostly seen in older or highly formal writing. Not recommended for learners.
Variant with 迄 for まで; even rarer than the other kanji form. Archaic flavor.
Reduplication of いつ (when) plus まで (until) and も (even), literally 'until when-when even'. The doubling of いつ intensifies the sense of endless time.