'attemper' originates from Latin, specifically the word 'adtemperare', where 'ad-' meant 'to' or 'toward' and 'temperare' meant 'to mix' or 'to moderate'.

'attemper' entered English via Old/Middle French and Middle English forms derived from Latin 'adtemperare', eventually becoming the modern English 'attemper' and its derivatives such as 'attempering'.

Initially, it meant 'to mix or temper (materials)' in a literal sense, but over time it evolved into its current sense of 'to moderate, adjust, or bring into harmony'.