'augend' originates from Latin, specifically the Medieval Latin word 'augendus', where 'augere' meant 'to increase' and the gerundive '-ndus/-nda' indicated 'that which is to be (increased)'.

'augend' changed from the Medieval Latin gerundive 'augendus' (meaning 'that which is to be increased') into English mathematical usage as 'augend' during the development of algebra and arithmetic terminology in the early modern period.

Initially, it meant 'that which is to be increased' (in a literal sense), but over time it evolved into the current technical meaning 'the quantity to which another is added' in arithmetic.