triptych. ‘Picture or carving in three compartments side by side, the lateral ones being usually subordinate’, though connected in subject, ‘and hinged so as to fold over the central one’, often forming a late-medieval altarpiece, called Flügelaltar in Germany (where some of the finest carved and painted examples can be found). When closed, the part visible (i.e. the backs of the folding leaves) often displayed grisaille paintings.

Bibliography

Chilvers Osborne & Farr (eds.) (1988);
Gwilt (1903);
Oxford English Dictionary (1933)

trip·tych / ˈtriptik/ • n. a picture or relief carving on three panels, typically hinged together side by side and used as an altarpiece. ∎  a set of three associated artistic, literary, or musical works intended to be appreciated together.

triptych tablet or card folded in three XVIII; picture or carving hinged in three divisions XIX. f. TRI-, after DIPTYCH.

triptych a picture or relief carving on three panels, typically hinged together vertically and used as an altarpiece. The word is recorded from the mid 18th century, and denoted originally a set of three writing tablets, hinged or tied together; it is formed from tri- ‘three’ on the pattern of diptych.

triptych Painting or carving consisting of three panels, traditionally used as an altarpiece. The panels may form one picture, or the outer panels may be separate and subordinate to the central picture.