A volatile liquid is one that evaporates or vaporizes quickly at room temperature. Not all volatile substances are liquids; some are solids.
In everyday language, "volatile" means to erupt emotionally or suddenly become angry or violent. It can also mean someone whose emotions swing up and down quickly. The word itself originated from a Latin word meaning "to fly" or a creature that flies (according to the site Reference), giving substance to the definition of the word as flighty or quick to change. Similarly, in chemistry, a substance that is volatile is quick to change, as it moves from a liquid to a vapor, which, in a sense, is "flying."