(1):

(v. t.) To soften, mollify, or moderate; to soothe; to temper; as, to attemper rigid justice with clemency.

(2):

(v. t.) To accommodate; to make suitable; to adapt.

(3):

(v. t.) To mix in just proportion; to regulate; as, a mind well attempered with kindness and justice.

(4):

(v. t.) To reduce, modify, or moderate, by mixture; to temper; to regulate, as temperature.