'forgettable' originates from the verb 'forget', which comes from Old English 'forgietan', where 'for-' meant 'away, opposite' and 'gietan' meant 'to grasp'.

'forgietan' transformed into the Middle English word 'forgeten', and eventually became the modern English word 'forget'.

Initially, it meant 'to lose remembrance of something', and this meaning has largely remained the same in modern usage.