Volatility 

A statistical measure of the variance of price or yield over time. Volatility is low if the price does not change very much over a short period of time, and high if there is a greater change.

Remarks: Bond funds including mutual funds (open-end and closed-end, actively managed and indexed), exchange-traded funds and unit investment trusts offer a convenient and affordable way to invest in a diversified portfolio of bonds, but a bond fund investment can differ from a bond investment in ways that are important to understand.