'carelessly-modified' originates from the combination of 'carelessly' and 'modified'. 'Carelessly' comes from 'careless', which originates from Old English 'carleas', where 'caru' meant 'care' and 'leas' meant 'free from'. 'Modified' comes from Latin 'modificare', where 'modus' meant 'measure' and 'facere' meant 'to make'.

'carelessly-modified' evolved from the combination of 'carelessly' and 'modified', which were used separately in Middle English and later combined in modern English.

Initially, 'carelessly' meant 'without care' and 'modified' meant 'altered'. Together, they evolved to mean 'altered without care'.