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Webster 1913 Edition

Noun.

[Gr. [GREEK] consisting of three layers or plates; [GREEK] (see

) + [GREEK], [GREEK], a fold, layer.]

Anything in three parts or leaves.

Specifically: –

(a)

A writing tablet in three parts, two of which fold over on the middle part.

(b)

A picture or altarpiece in three compartments.

triptych ‎(plural triptychs)

(art) A picture or series of pictures painted on three tablets connected by hinges.
(philately) A set of three se-tenant postage stamps that form a composite picture.

art: a picture or series of pictures painted on three tablets connected by hinges