lightener
1 of 2noun (1)
light·en·er ˈlīt-nər 
ˈlī-tᵊn-ər
plural lighteners
: a substance that makes something lighter in color
especially : a chemical substance used to lighten hair or skin
When my hair started getting darker in my early teens, my mother handed me a bottle of spray-on lightener to help me stay blond. 
Cybill Shepherd
Cybill Shepherd lightener
2 of 2noun (2)
plural lighteners
: one that makes something lighter in mood, weight, etc.
When cameras were not rolling, his off-beat humor made him a mood lightener among friends and colleagues, and he could play whatever role was asked of him. Emma Stickgold
Emma Stickgold
Word History
First Known Use
Noun (1)
1892, in the meaning defined above
Noun (2)
circa 1611, in the meaning defined above