adj.
  - not consistent or having a fixed pattern; liable to vary. 
▸Mathematics  (of a quantity) able to assume different numerical values.
 ▸Botany  & Zoology  (of a species) liable to deviate from the typical colour or form, or to occur in different colours or forms.
 - able to be changed or adapted. 
▸(of a gear) designed to give varying ratios or speeds.
 
n.
 a variable factor or quantity. 
▸Astronomy  a star whose brightness changes (regularly or irregularly).
 ▸
(variables)
 the region of light, variable winds to the north of the NE trade winds or (in the southern hemisphere) between the SE trade winds and the westerlies.
 
  Derivative
  
    - variability n.
  - variableness n.
  - variably adv.