In heraldry, vair is a "fur", a tincture which is simultaneously a two-coloured field treatment. It is found in a variety of colours, and appears in different arrangements, each with its own name.

It goes back, as does ermine, to a fur highly prized by the potentates of the Middle Ages: squirrel. The word vair is derived from the Middle English forms veir and vairé, meaning variegated fur (from the French vair, itself from the Latin varius, variegated).

The squirrel in question was apparently blue-grey on the back and white underneath, and was much used for the lining of cloaks. It was sewn together in alternating cup-shaped pieces of back and stomach fur, resulting in a pattern of grey-blue and grey-white which, when simplified in heraldic drawing and painting, became blue and white in alternating pieces. The species involved has never been accurately identified.

In the Cinderella fairy tale, the slippers were of vair fur, and the homonym "verre" must have been erroneously used by the translator, resulting in the impossible "glass slippers".

In the oldest records vair is represented by means of straight horizontal lines alternating with vertical wavy or nebuly lines (sometimes blazoned as vair ondé or vair ancien).

A fur of other colours than argent and azure is referred to as vairy (or vairé) of <metal> and <colour>