Definition of "Lighten" :

verb: alleviate or remove (pressure or stress) or make less oppressive

"Lighten the burden of caring for her elderly parents."

verb: become lighter

"The room lightened up."

verb: make more cheerful through the use of color

verb: become more cheerful

"After a glass of wine, he lightened up a bit."

verb: reduce the weight on; make lighter

"She lightened the load on the tired donkey."

verb: make more cheerful

"The conversation lightened me up a bit."