'accidentally-kept' originates from the combination of 'accidentally' and 'kept', where 'accidentally' comes from Latin 'accidentalis', meaning 'happening by chance', and 'kept' is the past participle of 'keep', from Old English 'cēpan', meaning 'to seize or hold'.

'accidentally-kept' combines the adverb 'accidentally' with the past participle 'kept', forming a modern English adjective.

Initially, 'accidentally' meant 'by chance', and 'kept' meant 'held or retained'. Together, they describe something retained without intention.