lighten

Some common synonyms of lighten are allay, alleviate, assuage, mitigate, and relieve. While all these words mean "to make something less grievous," lighten implies reducing a burdensome or depressing weight.

The meanings of allay and lighten largely overlap; however, allay implies an effective calming or soothing of fears or alarms.

The words alleviate and lighten can be used in similar contexts, but alleviate implies temporary or partial lessening of pain or distress.

The synonyms assuage and lighten are sometimes interchangeable, but assuage implies softening or sweetening what is harsh or disagreeable.

While in some cases nearly identical to lighten, mitigate suggests a moderating or countering of the effect of something violent or painful.

The words relieve and lighten are synonyms, but do differ in nuance. Specifically, relieve implies a lifting of enough of a burden to make it tolerable.