1. : one of a limited number of ways in which a point or a body may move or in which a dynamic system may change, each way being expressed by an independent variable and all requiring to be specified if the physical state of the body or system is to be completely defined
2. : a capability of variation possessed by a system by reason of the variability of one of its factors (as temperature, pressure, or concentration)
the system water-water vapor has one degree of freedom because when either temperature or pressure is arbitrarily fixed the other is no longer variable
— see phase rule
3. : the number of intervals in which the frequency may be arbitrarily assumed in a statistical distribution with equal intervals of the statistical variable