A song that really moved you and changed the way you look at music and that you think back on often is an example of a song that would be described as unforgettable.
- un′for·get′ta·bil′i·ty un′for·get′ta·ble·ness
(comparative more unforgettable, superlative most unforgettable)
- Which is very difficult to forget
- The things he subjected me to were horrible and unforgettable