Chemistry Evaporating readily at normal temperatures and pressures. Chemistry That can be readily vaporized. Tending to vary often or widely, as in price: the ups and downs of volatile stocks. Inconstant; fickle: a flirt's volatile affections. Lighthearted; flighty: in a volatile mood. Ephemeral; fleeting. Tending to violence; explosive: a volatile situation with troops and rioters eager for a confrontation. Flying or capable of flying; volant.