'stepwise-altered' originates from the combination of 'stepwise' and 'altered', where 'stepwise' means 'in a series of steps' and 'altered' means 'changed'.

'stepwise' and 'altered' have been used in English since the 16th century, combining in modern usage to describe a gradual change.

Initially, 'stepwise' referred to a manner of progression, and 'altered' meant 'changed'. Together, they describe a gradual change.