1. adjective /ˈveə(ɹ).i.ə.bl̩,ˈveɹ.i.ə.bl̩,ˈvæɹ.i.ə.bl̩/
a) able to vary
b) likely to vary
Syn: alterable, flexible, changeable, mutable, fickle, fluctuating, inconstant, shifting, unstable, unsteady, varying, aberrant
2. noun /ˈveə(ɹ).i.ə.bl̩,ˈveɹ.i.ə.bl̩,ˈvæɹ.i.ə.bl̩/
a) something that is variable
There are several variables to consider here.
b) something whose value may be dictated or discovered
Wikipedia foundation.