to modify or moderate by mixing or blending with something different or opposite.
2.
to regulate or modify the temperature of.
3.
to soothe; mollify; mitigate.
4.
to accommodate; adapt (usually followed by to).
Origin: 1325–75; Middle English attemperen < Latin attemperāre to adjust (see at-, temper); replacing Middle English attempren < Middle French attemprer < Latin, as above