Volatility

the degree of variation of a trading price series over time, usually measured by the standard deviation of logarithmic returns

In economics, the term volatility is used to measure how much the price or value of an economic good or service changes over time. Goods or services where the price changes a lot are said to have a high volatility, those that don't have a low volatility. The word come from the Latin verb "volare" meaning "to fly".