#1 buoyancy n. [perkiness] cheerfulness that bubbles to the surface. wn
#2 buoyancy n. [airiness] the property of something weightless and insubstantial. wn
#3 buoyancy n. the tendency to float in water or other liquid. wn
#4 buoyancy n. [irrepressibility] irrepressible liveliness and good spirit; "I admired his buoyancy and persistent good humor". wn
vizzz