'expectedly-decreased' originates from the combination of 'expectedly' and 'decreased', where 'expectedly' comes from 'expect' meaning 'to anticipate' and 'decreased' from 'decrease' meaning 'to reduce'.

'expectedly' evolved from the Latin word 'expectare', and 'decreased' from the Latin 'decrescere'.

Initially, 'expectedly' meant 'in a manner that was anticipated', and 'decreased' meant 'to become less'. The combined form retains these meanings.