Synonym: exceptional, extraordinary, memorable, notable, noteworthy, remarkable. Similar words: regrettable, regrettably, unforeseeable, forgetting, forget about, unfavorable, unfavourable, unflappable. Meaning: [‚ʌnfə(r)'getəbl] 
adj. impossible to forget.
adj. impossible to forget. (91) The old days are memories unforgettable , are sprites you can not touch but can always feel.
More similar words: regrettable, regrettably, unforeseeable, forgetting, forget about, unfavorable, unfavourable, unflappable, attainable, unfathomable, tablet, table, notable, stable, unattainable, eatable, mutable, tableau, potable, unenforceable, unstable, suitable, vegetable, portable, immutable, constable, excitable, habitable, on the table, tractable.