Jerk (in British English, jolt) is the derivative of acceleration with respect to time. Yank is mass times jerk, or equivalently, the derivate of force with respect to time. Jerk is a vector; there is no generally used term to describe its scalar value.
The units of jerk are metres per a second cubed (m.s-3). There is no universal agreement on the symbol for jerk, but j is commonly used.
Jerk is used at times in engineering. Some fragile or precision objects can be safely subjected not only to a maximum acceleration, but also a maximum jerk.
Higher derivatives of velocity than jerk also exist, but they are rarely necessary, and hence lack agreed upon names, although many suggestions have been made.