The tendency of an asset’s price to rise and fall, seemingly randomly.
Volatility refers to the tendency of the price of an asset or commodity to fluctuate consistently. This tendency is measurable in mathematical/statistical terms, especially with reference to the asset price’s standard deviations set against its annual return. Thus, volatility is traditionally associated with risk and unpredictability, such that volatile assets are those considered to be very risky and unstable.
The crypto market has been described many times by experts as a market of high volatility. This is because a large fraction of the values of market commodities (crypto assets, that is) are driven by trader perceptions. But the market is gradually becoming systematized, meaning that it is not as volatile as it used to be.