Noun

An act of showing joy.

:There was much rejoicing when the good news finally arrived.

* 1842 , Edward Bulwer Lytton, The Disowned (page 286)

But what are your foot-ploddings, your ambulating rejoicings , to the free etherealities which our courser's light bound and exultant spurnings of the dull earth bring to the spirit!

Noun

(uncountable)  The state of being happy.

* {{quote-book, year=1963, author=(Margery Allingham)

, title=(The China Governess) , chapter=2 citation , passage=Now that she had rested and had fed from the luncheon tray Mrs. Broome had just removed, she had reverted to her normal gaiety .  She looked cool in a grey tailored cotton dress with a terracotta scarf and shoes and her hair a black silk helmet.}}

(countable)  Merrymaking or festivity.