'roughly-split' originates from the combination of 'roughly' and 'split', where 'roughly' meant 'approximately' and 'split' meant 'to divide'.

'roughly' and 'split' were combined in modern English to form the adjective 'roughly-split'.

Initially, 'roughly' meant 'approximately' and 'split' meant 'to divide', and this meaning has largely remained the same in modern usage.