'unintentionally-lost' originates from the combination of 'unintentional' and 'lost', where 'unintentional' is derived from 'un-' meaning 'not' and 'intentional' meaning 'done on purpose', and 'lost' from Old English 'losian' meaning 'to perish'.

'unintentionally-lost' combines the modern English words 'unintentional' and 'lost', reflecting a state of being lost without intent.

Initially, 'lost' meant 'to perish or be destroyed', but over time it evolved to mean 'misplaced or not found', while 'unintentional' has maintained its meaning of 'not done on purpose'.