'Joyousness' definitions:

Definition of 'joyousness'

noun

The emotion of great happiness [syn: joy, joyousness, joyfulness] [ant: sorrow]

From: GCIDE

Joyous \Joy"ous\, a. [OE. joyous, joious, joios, F. joyeux.See Joy.] Glad; gay; merry; joyful; also, affording or inspiring joy; with of before the word or words expressing the cause of joy. [1913 Webster]
Is this your joyous city? --Is. xxiii. 7. [1913 Webster]
They all as glad as birds of joyous prime. --Spenser. [1913 Webster]
And joyous of our conquest early won. --Dryden.
Syn: Merry; lively; blithe; gleeful; gay; glad; mirthful; sportive; festive; joyful; happy; blissful; charming; delightful. -- {Joy"ous*ly}, adv. -- {Joy"ous*ness}, n. [1913 Webster]