Jubilance is what you feel when you're happy, joyful, or triumphant. The jubilance of a high school football team that finally wins a game after a season of losses is wonderful to see.
When you're practically overcome by happiness, you're experiencing jubilance, a celebratory kind of joy. You might enjoy the jubilance of your favorite actor winning an Academy Award, or the jubilance of a little boy jumping excitedly at his birthday party. The word comes from jubilant, which is rooted in the Latin jubilare, literally "to call to someone," but used in Christian writing (including Milton) to mean "to shout for joy."