A Joy

1. A feeling of extreme happiness or cheerfulness, especially related to the acquisition or expectation of something good. Joy - Wikipedia
2. Anything that causes such a feeling.
3. Luck or success; a positive outcome.
4. (obsolete) The sign or exhibition of joy; gaiety; merriment; festivity.

Antonyms

• (feeling of happiness): infelicity, joylessness, unhappiness, unjoy