buoy·ant 
(boiənt, byənt)
(boiənt, byənt)adj.
1. Having or marked by buoyancy: a buoyant balloon; buoyant spirits.
2. Lighthearted; gay: in a buoyant mood.
[Spanish boyante, present participle of boyar, to refloat a boat, from boya, buoy, from Old French boue; see BUOY.]
buoyant·ly adv.