The term 'make less serious' can be expressed in two ways: LIGHTEN (7 letters) and PALLIATE (8 letters). LIGHTEN is a verb meaning to make something less heavy or burdensome, either literally or figuratively. For example, one might LIGHTEN the load of a backpack by removing some items, or LIGHTEN the mood of a room by making a joke. PALLIATE is also a verb, meaning to make something less severe or intense, usually referring to pain or suffering. For example, one might PALLIATE a headache with medication, or PALLIATE the effects of a natural disaster with aid.