Mirth

Definition: overt happiness or merriment

From context, this usually means externally obvious happiness – laughing, dancing, etc. It might be more accurately described as celebration.

It’s from the Old English word for “merry.”

Why I Looked It Up

I sort of knew what this was from context, but was curious if there was a specific definition apart from general happiness.

I found this in a book which I can’t remember (this was quoted from a personal letter – at least, it looks that way from the picture of the page that I took):

By all ordinary rules, I ought to have laughed more loudly at these extravagances than at the far milder theories which had previously moved me to mirth; yet something in the tone of the letter made me take it with paradoxical seriousness.

Note that the writer correlates mirth with laughing loudly.