vol·a·tile   [vol-uh-tl, -til or, especially Brit., -tahyl] ... adjective

1. Flying or capable of flying; volant, volare.
2. tending or threatening to break out into open violence; explosive.
3. changeable; mercurial; flighty; lighthearted; flighty: a volatile disposition.
4. tending to fluctuate sharply and regularly. Inconstant; fickle: a flirt's volatile affections.
5. fleeting; transient: ... a volatile beauty.