variability

The quality, state, or degree of being variable or changeable.

The quality or state of being variable; variableness.

In biology, ability to vary; capability of variation; susceptibility to modification under conditions of environment, whether inherited or acquired; that plasticity or modifiability of any organism in virtue of which an animal or a plant may change in form, structure, function, size, color, or other character, lose some character or acquire another, and thus deviate from its parent-form; also, the kind or rate of variation in a given instance; the fact or act of varying. See variation, 8, variety, 6.

In astronomy, the fact that a star or nebula changes its brightness in a more or less periodic manner.

The power possessed by living organisms, both animal and vegetable, of adapting themselves to modifications or changes in their environment, thus possibly giving rise to ultimate variation of structure or function.