buoyancy

noun

1. (countable, uncountable)The upward force on a body immersed or partly immersed in a fluid.
2. (countable, uncountable)The ability of an object to stay afloat in a fluid.
3. (broadly, countable, figuratively, uncountable)Resilience or cheerfulness.

   “With how much lighter a step, with how much brighter an eye, did Francesca wander through the forest, even in the last desolation of autumn, than she did in all the bloom and buoyancy of spring!”