Open English Wordnet
Nouns
(n)extenuation, mitigation, palliationto act in such a way as to cause an offense to seem less serious
(n)extenuation, mitigationa partial excuse to mitigate censure; an attempt to represent an offense as less serious than it appears by showing mitigating circumstances
(n)moderation, mitigationthe action of lessening in severity or intensity“the object being control or moderation of economic depressions”