Merriment is a related term of cheerfulness.
As nouns the difference between merriment and cheerfulness
is that merriment is a state of enjoyable exuberance while cheerfulness is the state of being cheerful; joy.
merriment
English
Noun
a state of enjoyable exuberance
*
playful fun
*
cheerfulness
English
Noun
(-)
The state of being cheerful; joy.