Meaning of VARIABLE in English
1》 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.
2》 able to be changed or adapted.
↘(of a gear) designed to give varying ratios or speeds.
■ noun a ~ factor or quantity.
↘ Astronomy a star whose brightness changes (regularly or irregularly).
↘( ~s ) the region of light, ~ winds to the north of the NE trade winds or (in the southern hemisphere) between the SE trade winds and the westerlies.
Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004