buoyant >> /ˈbɔɪənt/
Definition: [adjective] Able or apt to stay afloat or rise to the top of a liquid or gas.
Example: The most buoyant body parts rise first, leaving the head and limbs to drag behind the chest and abdomen.
Definition: [adjective] Cheerful and optimistic.
Example: the conference ended with the party in a buoyant mood
Definition: [adjective] (of an economy, business, or market) involving or engaged in much activity.
Example: car sales were not buoyant