Something that is variable.

Something whose value may be dictated or discovered.

(mathematics) English Wikipedia has an article on:Variable (mathematics)Wikipedia A quantity that may assume any one of a set of values.

(mathematics) A symbol representing a variable.

(astronomy) A variable star.

(nautical) A shifting wind, or one that varies in force.

(nautical, in the plural) Those parts of the sea where a steady wind is not expected, especially the parts between the trade-wind belts.

Able to vary or be varied.

Likely to vary.

Marked by diversity or difference.

(mathematics) Having no fixed quantitative value.

(biology) Tending to deviate from a normal or recognized type.