buoyant capricious elusive erratic fickle resilient ticklish unsettled unstable elastic ephemeral fugitive gay imponderable light transient variable airy effervescent expansive fleeting flighty flippant frivolous fugacious gaseous giddy impermanent inconsistent inconstant lively lubricious mercurial momentary playful short-lived sprightly subtle temperamental transitory unsteady up-and-down vaporous whimsical