noun
mirth
MURTH/mɜːrθ/
Cheerful amusement often expressed in laughter.
The friends' warm laughter expresses their shared mirth.

Etymology
The root shared with “merry” originally described things that were pleasant or pleasing. With the quality-noun ending, “mirth” named joy and pleasure broadly before developing its familiar sense of merriment and laughter.
In context
he burst into deep-chested mirth. The King, the Prince and Chandos, who had watched the scene from a distance, too much amused by it to explain or interfere, rode up weary with laughter
More examples
- He struggles to hide his mirth during the serious meeting.
- Her eyes sparkle with mirth as she tells the story.
- The unexpected punch line sends us into fits of mirth.
Forms
mirthful adjective — Full of joy and amusement.
mirthless adjective — Lacking genuine joy or amusement.