means Something that can change or take different values; in math and programming, a named placeholder that stands in for a quantity that isn't fixed.

from From Latin variabilis, 'changeable,' built on variare, 'to change or vary,' which itself traces to varius, meaning 'speckled, diverse, many-colored.' So at its root a variable is something dappled and inconstant — the word arrived in English through Old French in the late medieval period, long before it was conscripted into algebra and, later, code.