'carelessly-completed' originates from the combination of 'careless' and 'complete', where 'careless' comes from Old English 'carleas', meaning 'free from care', and 'complete' from Latin 'completus', meaning 'filled up'.

'careless' evolved from Old English 'carleas', and 'complete' from Latin 'completus', eventually forming the modern English compound adjective 'carelessly-completed'.

Initially, 'careless' meant 'free from care', but over time it evolved to mean 'negligent', while 'complete' retained its meaning of 'finished'.