happiness
幸福
Anhedonia
Aversion to happiness
Brain stimulation reward
Depression
Euphoria
Extraversion, introversion and happiness
Hedonic treadmill
Pleasure
Reward system
Sadness
https://source.unsplash.com/featured/?happiness#.png
/suto3/google.iconhappiness
image happiness
define happiness
wikipedia happiness
weblio happiness
kotobank happiness
jisho happiness