noun-modifying (irregular)
unforgettable; never to be forgotten
Literary or emotive prenominal modifier; often used in poetic or reflective contexts to describe memories, people, or experiences that cannot be forgotten.
Unforgettable memories remain in my heart.
He is an unforgettable person.
Standard kanji spelling using 得ぬ for the negative potential.
Kana spelling of 得ぬ; slightly less formal but still common.
Compound of 忘れ (the continuative form of 忘れる 'to forget') + 得ぬ (the classical negative potential form of 得る 'to be able to'), literally 'cannot forget'.