Same as dispersion. In finance, volatility usually refers to the rate at which a financial variable, such as stock price, moves up or down over time. Volatility is measured by the standard deviation or, sometimes, by the variance. The (absolute) empirical volatility of a stock price is usually calculated as the annualized standard deviation of daily change in price. A measure of the volatility of a stock relative to the market is its beta coefficient.
Reference: Oxford Press Dictonary of Economics, 5th edt.